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seed bullet

shoot seeds and grow trees with them
  (+11, -2)(+11, -2)
(+11, -2)
  [vote for,
against]

This bullet would have a plant seed inside it. It may be that battlefields and mass graves will turn into glorious forests in not too much time.

Poppies are traditional but I think fruits and nuts would be nice. Perhaps people would ponder the forests thus created and decide something probably isn't worth fighting over.

Voice, Oct 28 2012

multiplanter Tree_20Planting_20Machine_20Gun
How does your garden grow? Blam blam blam blam! [lurch, Oct 28 2012]

chilly veggies Plane_20planting
[rayfo] goes not just green, but coool green [lurch, Oct 28 2012]

Plow and plant Cannon_20seeder
[bungston] thinks in higher calibers [lurch, Oct 28 2012]

Thermal imaging studies of bullets in flight http://www.advanced...ullet-Heating/1$180
[spidermother, Oct 28 2012]

Ah, here we go... Bonsai_20Bullets
African or European bullet? [normzone, Oct 29 2012]

Square Cube law http://en.wikipedia...iki/Square-cube_law
"Thus, just scaling up the size of an object, keeping the same material of construction (density), and same acceleration, would increase the thrust by the same scaling factor. This would indicate that the object would have less ability to resist stress and would be more prone to collapse while accelerating." [Voice, Oct 31 2012]

Maybe we should get [Alterother] one of these... Cat_20food_20can_20shotgun
[normzone, Oct 31 2012]

Pyrotechnic Planting Pyrotechnic_20planting
Related idea [csea, Nov 08 2012]

Baked http://www.flowershell.com
[AusCan531, Mar 08 2014]

Voice and Alterother should try this. http://xkcd.com/827/
[AusCan531, Mar 09 2014]

It's happening! http://newatlas.com...dable-bullet/47302/
[Voice, Jan 09 2017]

[link]






       Unfortunately, bullets get rather hot when fired - more than hot enough to render a seed unviable.
8th of 7, Oct 28 2012
  

       Do you have any data on that, [8th]?   

       How would a bullet heat up, we ask ourselves. Well, first because it is in contact with the hot gases produced by the propellant. These are presumably at several thousand degrees Celsius.   

       However, the bullet is in contact with these gases for only the few milliseconds it takes to leave the barrel.   

       Second, it experiences friction with the sides of the barrel. However, it is probably safe to assume that the temperature generated at the interface is lower than the melting point of the barrel, say 1000°C. And the bullet is in contact with the barrel walls for, again, a few milliseconds.   

       So, how much heat can be transferred to a bullet in (say) 2 milliseconds, by a combination of (a) transfer from hot gas behind the bullet and (b) transfer from the ?1000°C? interface between bullet and barrel?   

       I contend that (a) is negligible (I can move my finger swiftly through a bunsen flame, exposing it to hot gases for at least a few milliseconds, without perceptible burnage). I also contend that (b) is negligible, based on thermal capacities and conductivities.   

       I hencetherefore conclude and contend that a bullet is not especially hot as it leaves the gun.   

       It also occurs to me that, in all the episodes of CSI, Quincy, Columbo, Poirot and the like that I have watched, it has never been suggested that bullets are hot when they leave the gun. If they were, then one could determine whether a person had been shot from close range by noting the burns caused by the still-hot bullet.   

       There are, incidentally, thermal imaging studies of bullets in flight, which show its surface temperature to be very high (perhaps 300°C). However, this is the temperature of the surface of the bullet within milliseconds of leaving the barrel. During this time, the frictional heat has not penetrated the body of the bullet significantly, and hence only the outermost layer is hot; when that heat energy distributes itself through the mass of the bullet, it will cause only a very modest temperature increase in the centre.   

       Gentlemen of the jury, the defence rests.
MaxwellBuchanan, Oct 28 2012
  

       Air friction and deformation (both in rifling and at impact). Frictional heating at impact.   

       Based on anecdotal evidence (Mythbusters picking them up and commenting) bullets retain heat for some time after impact.   

       More to the point if the seed is actually in the center of the bullet, I believe it is unlikely it will manage to break out while sprouting.
MechE, Oct 28 2012
  

       And yet bullet wounds don't normally show burning or scorching?
MaxwellBuchanan, Oct 28 2012
  

       Based on direct observation (picking them up and immediately dropping them) bullets retain heat for some time after impact. If dropped into a cup of water, there is a substantial sizzling.
8th of 7, Oct 28 2012
  

       The volume of material in contact with a bullet wound is high, and the duration of contact, for the first several inches, is low. This would limit scorching damage to the first layer or two of cells. Since the cells are experiencing physical insult much, much greater than thermal, it is likely not to present as burning.
MechE, Oct 28 2012
  

       // bullets retain heat for some time after impact//   

       Most of the heat, I would venture to vouchsafe, comes from the impact, and consequent deformation of the bullet.   

       I still contend that a bullet, on leaving the gun, has a very thin hot skin from friction with the barrel, but an average temperature only slightly somewhat above ambient.
MaxwellBuchanan, Oct 28 2012
  

       You need to know: the muzzle velocity of the round, and mass. This will allow you to calculate the muzzle energy.   

       Then you need to do the exterior ballistics portion: needs the above, plus distance to target and ballistics coefficient. Or, chronographically measured velocity at target. The difference in energy between muzzle and target all gets lost as heat. Some goes to air; some goes to the projectile; a shape that's good for a projectile is bad for cooling. The ratio is probably more easily measured than calculated.   

       If you use a cast lead bullet in a .17 Remington (very small mass, not a really good ballistic coefficient) and pump up the velocity to higher-than-reasonable levels (say, 4200 fps) you can get a situation where the bullet will vanish (melted, then torn apart by centripetal force) before it gets to a target 100 yards away.
lurch, Oct 28 2012
  

       //I still contend that a bullet, on leaving the gun, has a very thin hot skin from friction with the barrel, but an average temperature only slightly somewhat above ambient.//
MaxwellBuchanan, Oct 28 2012
  

       The whole heat debate is just a matter of engineering. Use a metal that fragments upon impact OR doesn't retain heat well and you're fine.
Voice, Oct 28 2012
  

       [+] I like the image.   

       Realistically I don't think temperature is that much of a problem: if you're going to design a bullet that stays in one piece through the barrel and flight, but disintegrates after it's plowed through a couple of inches of earth, while cushioning the seed against the brutal acceleration and deceleration of being fired and hitting the earth, you may as well make it heat-retardant as well.
FlyingToaster, Oct 28 2012
  

       // Use a metal that fragments upon impact OR doesn't retain heat well and you're fine. //   

       Either one of these qualities alone would disqualify a material for use as a bullet jacket. Jacket material must be ductile, a property normally found in soft-ish, conductive metals such as copper.
Alterother, Oct 28 2012
  

       The thermal energy is going to be pretty much one half the mass times the velocity squared (the kinetic energy) (conservation of energy says all the energy you didn't get rid of in flight ends up in the bullet hole). So, I think it would be reasonable to make the bullet into a discarding sabot style penetrator.   

       Somewhere here on the 'bakery, we should be able to find air-dropped icicle planting darts which should be applicable/adaptable.
lurch, Oct 28 2012
  

       I second what [lurch] wrote, and was about to write something similar. The bullet consist of a group of atoms all moving in mostly the same direction, during the trajectory the bullet travels. Relative to each other, during the flight of the bullet, those atoms are not especially hot, and this is the temperature described in the first few annos here.   

       When impact happens, though, the proper way to think of it is in terms of atoms colliding with other atoms. So, while the BULLET may stop moving, even passing on SOME of its kinetic energy in the process, many of the atoms of the bullet will still have a lot of their in-flight kinetic energy --but they are no longer moving in parallel all-together. Each atom now exhibits that kinetic energy as increased random motion relative to the other atoms in the bullet. There will be a very significant temperature rise in the bullet at impact.   

       Note that even if you protect the seed from the atoms of the bullet, you still have the same problem described above, with respect to high-speed seed-atoms suddenly being forced to stop moving all-together. The seed's temperature will rise at impact even if there was no accompanying bullet!
Vernon, Oct 28 2012
  

       It's not the seeds that need to be heated. Many species of pine common to your Northern hemisphere drop their seeds in tough casings which only open after exposure to high temperatures. The same is true of the Australian species. Pine cones are fibrous and insulating, to keep the seeds viable by protecting them from the heat.
8th of 7, Oct 29 2012
  

       Yes, but it won't be heavy enough to be useful. That's why bullets are made of lead.   

       Some facts:   

       For 20 7.62 x 51mm full-jacketed rounds (standard NATO load) fired from an L4 LMG at 50m into clean, dry sand at 11C, examination of the 17 projectiles recovered within 30 seconds after the last round was fired gave a range of temperatures from 122C to 193C using a non-contact thermometer.   

       The projectiles were still significantly above ambient after 10 minutes of air cooling and caused significant discomfort when touched. Some people just won't be told.   

       It is not unreasonable based on these figures to extrapolate that the bulk temperature of the projectile in flight exceeds 200C for a significant portion of its travel. The materials involved lend themselves to rapid and and homogenous heat distribution.   

       Further research is planned, as soon as the existing mess has been cleared up.
8th of 7, Oct 29 2012
  

       Forget the bullet part, just issue the armed forces with seed drills, seed fiddles and the like instead of guns.
pocmloc, Oct 29 2012
  

       Isn't that the Peace Corps ?
8th of 7, Oct 29 2012
  

       //bulk temperature of the projectile in flight exceeds 200C for a significant portion of its travel//   

       Only if you assume that the bullet did not heat up significantly upon impact. Sand or no sand, that kinetic energy is going to go somewhere.   

       The correct way to answer this question would be to suspend [8th] beneath a hydrogen balloon. As the balloon rises, someone on the ground will fire repeatedly at [8th]. At some point, the altitude of the balloon will match the peak altitude of the bullet. [8th] can then pluck this bullet from the air as it peaks, and check its temperature, without the distorting effects of impact warming.   

       I am happy to make the balloon available.
MaxwellBuchanan, Oct 29 2012
  

       We are sure you are.   

       We have a simpler scheme.   

       A batch of bullets are drilled in the base with a 2mm hole extending 80% of the length. Into this hole is placed a granular material of known melting point. The filling hole is then sealed with a threaded plug to prevent ingress of propellant gases.   

       The bullets are crimped into cartridge cases and sequentially fired at 45 degrees elevation to give the maximum time of flight. The target area will not be very large. A suitable expanse of dry sand should be easy to locate. This area is searched* by poorly- paid illegal immigrants equipped with metal detectors and the recovered bullets are unplugged and the contents of the bore examined. If the test material has melted and recrystallised, this will be immediately evident.   

       *Results will be obtained faster if the retrieval operation is concurrent with the firing. However, this must be weighed against the risk of samples being damaged by impact with human tissue. On the plus side, these samples will be significantly easier to locate.
8th of 7, Oct 29 2012
  

       Regarding the thermal imaging in [spidermother]'s link: it shows most of the surface of the bullet to be at something close to ambient temperature. The tippiest tip of the tip, and small patches on the side (presumably those which had been in contact with the rifling) are much hotter, but clearly these hot areas are only on the surfacemost surface of the bullet.   

       Thus, the great majority of the bullet's mass, and indeed its core, are at close to ambient temperature.
MaxwellBuchanan, Oct 29 2012
  

       // only on the surfacemost surface of the bullet //   

       <sigh>   

       Did you read the bit about how conductive metals like cupro-nickel and lead are ?
8th of 7, Oct 29 2012
  

       //Did you read the bit about how conductive metals like cupro-nickel and lead are ?//   

       Yes. And while I was at it, I read the Wikipedia page that says that lead has one of the lowest thermal conductivities of any metal. Most cupro- nickels are also very poor conductors of heat.   

       Did you read the bit in Borging For Dummies about how you need to think before writing?   

       Metals are isotropic. That means that heat will conduct equally in all directions. Hence, if there are narrow stripes of heat down the sidey sides, and a small point of heat at the tippy tip, that means that the heat has not had time to conduct significantly in any direction, and remains close to where it was generated. Thus, your very argument proves that the bullet in the image has a cool centre.   

       By taking thermal masses into consideration, you will also find that a few narrow, shallow areas of hot metal will not cause the remainder of the bullet to become especially hot, even when they have had time to conduct uniformly. I would estimate that less than 10% of the bullet's mass is "hot" (>300°C), which will result in an eventual rise of <30°C in the core of the bullet, impact heating notwithstanding.   

       I'm resting my case again, but if this continues I may just get one with wheels.
MaxwellBuchanan, Oct 29 2012
  

       Get yourself one of those golf buggy things - tomorrow, weather permitting, a little ballistic calorimetry will be taking place ...
8th of 7, Oct 29 2012
  

       You seem to be resting your case at a point very near to the muzzle of the gun, which may not be the best... Yes, the temps at that point are probably not seed-killing - but it's not a useful situation because you can't produce a realistic scenario in which the seed is "planted" at that point. (Unless you are travelling in an aircraft, pointing the gun back along your path, and firing the bullet to a velocity near to "at rest" with reference to the planting bed. Or you're waving your "inertia-b-gone" wand...)   

       I think it's interesting to note that, in those infrared images, the bullet's tip has heated to 170C. It hasn't been rubbing on the barrel, not subjected to burning gasses, it's just air friction - from passing through 5 feet (or slightly less) of air. (3 feet outside the barrel - the other foot-and-a-half to two feet probably don't count, 'cause there's no appreciable mass flow past the bullet.)   

       I would love to see them show further pictures - say 10 feet and 20 feet downrange. Then you'd get a look at rate-of-change of the various hotspots.   

       Just as an "it doesn't matter, but...", I kind of doubt their description of the heat-image-bloom at the bullet's base being a "reflection" of the muzzle flash. That would be a diffuse light source, symmetrical aroud the axis of the bullet's flight; the reflection should have an annular component to the phong. I think it's more likely a local hotspot on the metal, and heated gasses trapped in the boat-tail's slipstream.   

       Anyway, in the duel between [m'lud] and [hisBorgnitude], we're doomed to see no winner because the two of you are talking on different fields of honor. What say we hold all further insults, examples, theories, and mathematics until you come to an agreement about what ballistic point is to be the subject of controversy?   

       (Decide quickly, and let the weather permit, because I wouldn't want to miss experimental gunfire. I just want it to miss me.)
lurch, Oct 29 2012
  

       666.   

       // the other foot-and-a-half to two feet probably don't count, 'cause there's no appreciable mass flow past the bullet. //   

       <cough>   

       Since the obturation is never perfect- at least in a rifled barrel- some propellant gas does escape forward of the projectile, and can act as a lubricant between the bore and the jacket.   

       The effect is particularly noticeable in larger calibre weapons that have a driving band rather than relying on jacket-to-bore contact.   

       The velocity of the propellant gas forward of the ogive is only a little more than that of the projectile due to pressure piling along the bore, but is visible in some slo-mo imaging as a small burst of flame before the projectile starts to exit the muzzle.
8th of 7, Oct 29 2012
  

       That's a nasty cough there. It's too bad the lack of genetic diversity in the commune leaves such openings for extinction events from simple allergies.   

       You might have noticed that I was talking about frictional heating of the bullet tip. In that context, the blow-by - which is certainly of sufficient concern to necessitate driving bands, ball- patching, gas checks, or wadding, depending on what weapon you use - isn't going to cause much of a point-specific hot spot by impingement heating; would you not agree?
lurch, Oct 29 2012
  

       //You seem to be resting your case at a point very near to the muzzle of the gun, which may not be the best//   

       The manufacturers of the MaxCo Gatlin' Gro (which, strangely, we managed to patent under 'first to file' law) guarantee only the viability of the seed at the point of departure from our apparatus. We can hardly be held responsible for the laws of physics once these act outside our product, can we?   

       //What say we hold all further insults// And the fun of that would be? I consider a good argument with [8th] to be my main form of cardiovascular workout, especially whilst the junior under- pantrymaid is on leave. I am sure that his Borgness also relishes such peer-to-Peer exchanges. The fact that I'm always right is the most trifling technicality, I assure you.
MaxwellBuchanan, Oct 29 2012
  

       Little known fact: The server this site runs on is actually /powered/ by insults. In fact, given the low overhead of the Halfbakery, there's actually enough leftover energy to power a sunlamp for a medium- sized ficus plant standing next to the server rack.   

       It's all part of an ambitious project undertaken by the Goog to develop a clean alternative energy source fueled entirely by Reddit and 4chan.
ytk, Oct 29 2012
  

       Now thinking about Eggbert Flapdoodle, chicken thief. Shot in the ass last week, now with Acorn Squash coming out of his Gluteus Maximus. [+]
Grogster, Oct 29 2012
  

       Given that many seeds can survive boiling water poured over them (a recommended method to trigger germination for some hard-coated seeds), and impacts up to being struck lightly with a hammer, I would not be surprised if this could be made to work. The seed may need to be coddled in a little insulating wadding.   

       Military bullets are becoming increasingly lead-free, which changes some of the above analysis. (Aside: to me, that has always been the biggest problem with guns. The 'well, derr!' principle suggests that sending tonnage of neuro-toxic heavy metals fanging about, some of it ending up as fine particles, is basically a bad thing.)
spidermother, Oct 29 2012
  

       ////...we hold all further insults// And the fun of that would be?// We need not have misdirected, poorly thought out insults. Let them be highly topical, yet penetrating; well-considered inconsiderateness, cutting to the quick, through the slow, and onward to the stationery. In short, in the shorts.
lurch, Oct 29 2012
  

       //use seeds that only germinate when heated, like wot them Australian plants do//   

       Actually, studies show it is the chemicals in the smoke rather than heat which prompt germination. You can now buy 'smoked' native seeds here where the seedcase has been scored to allow for easier splitting and have been soaked in water which has previously had smoke percolated through it.
AusCan531, Oct 29 2012
  

       Quite so; although some seed capsules open when heated, thus heat indirectly triggers germination. But many Australian plants' seeds are capable of germinating after being heated.   

       //the bullet's tip has heated to 170C. It hasn't been rubbing on the barrel, not subjected to burning gasses, it's just air friction - from passing through 5 feet (or slightly less) of air. (3 feet outside the barrel - the other foot-and-a-half to two feet probably don't count, 'cause there's no appreciable mass flow past the bullet.)// I don't see why the bullet's tip would not be heated by the air it encounters while inside the barrel. Such heating is surely caused by compression rather than //mass flow past the bullet//, especially for supersonic bullets.
spidermother, Oct 29 2012
  

       According to the ballistics information for the 7.62X51 cartridge, as referenced on Hornady's web-site: A 150grn full-metal-jacket bullet fired at a muzzle velocity of 2940fps and a muzzle energy of 2878 foot.lbs will lose 440 fps of velocity and 796 foot.lbs of energy after traveling 200 meters (which is round about average engagement distance in my experience).
  

       150 grains = 9.72 grams
796 foot.lbs = 1080 joules
Ratio of copper to lead = 1:8 (wild guesstimate)
Specific heat capacity of lead = 0.160 joules per gram.degree
Specific heat capacity of copper = 0.385 joules per gram.degree
specific heat capacity of the bullet = 0.185
volume of cylinder 7.62mm diameter X 200 meter = 0.00912 m^3...
multiplied by 1.2 kg/m^3 (density of air) = 10.95g of air
  

       So as I see it, we have 1080 joules of energy absorbed between 9.72 grams of bullet and 10.95 grams of air. If we assume equal distribution, we should see a 282.43 degree Celsius increase in the temperature of the bullet caused by friction alone in the first 200 meters of flight.   

       This is not even factoring in the heat/pressure of combustion or the friction between the bullet and the barrel.   

       Of course, there are factors I am not accounting for due to ignorance as I am neither an aeronautical nor a thermal engineer... I'm just the poor sonuvabitch shooting the damn thing, but if my physics is anywhere wildly near to accurate; I definitely wont be picking up a recently fired projectile.
MikeD, Oct 30 2012
  

       Also, as to // Perhaps people would ponder the forests thus created and decide something probably isn't worth fighting over.//, I feel confident that implementation of this idea would only lead to phrases such as "I'm going to plant a forest in your chest", or "Keep running your mouth and there will be a tree where you're standing..."
MikeD, Oct 30 2012
  

       What [MikeD] said, subject to confirmation by practical testing.
8th of 7, Oct 30 2012
  

       I did a little practical testing with an M1911 (Kimber Covert II SOCOM, 7 1/4" bbl), a bucket of sand, and an engine thermometer, and determined that a .45 caliber FMJ slug excavated from reasonably dry sand within ten seconds of firing from point-blank range will have an external temp of 96-117 degrees F (from a test group of 14 rounds, ambient temp 68 degrees F).   

       Most were around 100. The 117 was unearthed considerably quicker than the others through sheer happenstance.   

       For those are questioning why I conducted my test with a handgun instead of the rifle calibers currently under discussion, let me assure you that when a high-velocity rifle bullet impacts a bucket full of sand, it more or less disintegrates, as does the bucket. That said, I'm absolutely certain that a 7.62 round is considerably hotter than a .45 leaving the barrel.
Alterother, Oct 30 2012
  

       // a .45 caliber FMJ slug excavated from reasonably dry sand within ten seconds of firing from point-blank range will have an external temp of 96-117 degrees F//   

       I have cancelled my order for a wheeled case, and have instead ordered a small plinth on which to rest my existing case.   

       I note that this very modest and seed-friendly temperature is noted after impact, and hence includes any impact heating.   

       I note also that, if the bullet is lead, the core of the bullet will not yet have equilibrated with the surface, within the ten seconds or so taken to retrieve said bullet.   

       Therefore, the centre of the bullet will be even cooler than the 96-117°F (36-47°C) of its surface.   

       In recognition of [MikeD]'s outstanding experimental efforts in the cause of proving me right, I hereby offer him [8th]'s best silver teapot, to be suitably engraved.
MaxwellBuchanan, Oct 30 2012
  

       I would like to point out, in the interest of further muddying the waters of this already Guinness-murky debate, that my trials were carried out under less than scientific conditions and that, shocking as it may seem, I have only 250 rounds of .45 acp remaining in my stockpile and thus committed only two magazines' worth of ammunition, hardly what I'd call a sufficient quantity for objective analysis.
Alterother, Oct 30 2012
  

       Nice Kimber, [Alterother]. I acquired an Ultracarry II, but have since come to regret it, as it's much too pretty to carry and shoot.   

       And it's difficult to find pine and oak loads for it.
normzone, Oct 30 2012
  

       Most Kimbers are too pretty for practical use, which I think is the ultimate irony of an artfully-designed firearm. I have a fondness for practicality in most things I own, but I must admit I tarried a bit over the Raptor and the Eclipse before selecting the SOCOM (which I now recall is actually the MDC trim package of Kimber's Covert II model <corrected above>). I specified the model for gun nuts like ourselves and for those 'bakers who want to look up specs like twist ratio, frame composition, and felt recoil to feed into their anal- retentive mathematical simulations.   

       A further thought occurs to me (stranger things have happened): a bullet from my M1911, fired from roughly waist-height, penetrates 6-8" of sand. While I'm no botanist, I do have some experience in the cultivation of certain species of flora, and to me such depth would seem rather prohibitive to healthy germination of a seed. I'll look around on the interwebby for the recommended planting depth for various tree seeds.
Alterother, Oct 30 2012
  

       "You're .... Home Economics ...!"   

       // I have only 250 rounds of .45 acp remaining in my stockpile //   

       <impressed>   

       Wow, you really do like to live life right on the edge, don't you ? Respect ...   

       </Impressed>
8th of 7, Oct 30 2012
  

       //penetrates 6-8" of sand//   

       6-8" deep, or just into a backstop? I would expect the depth to be relatively minimal, since most of bullet velocity is horizontal.
MechE, Oct 30 2012
  

       Doomsday survival nuts don't like miniguns. They need electric power to drive the feed system and they chew through too much ammo.   

       Doomsday survival nuts prefer simple, rugged kit; better an accurate single shot bolt-action that can take down your target at 1000m with the first shot rather than a noisy, heavy, temperamental spraygun for 5.56mm ...
8th of 7, Oct 30 2012
  

       //        Now I'm wondering whether [AO] is one of them doomsday survival nuts who solves everything with a gun.    //   

       Not at all. Those people are crazy. I do keep a modest 'just in case' stockpile, but mostly I have a bunch of ammo on hand because a dedicated shooter can burn through 300 rounds on a lazy Sunday afternoon. If it comes down to defending myself or my home with a gun, statistics show that I'll only need two or three rounds. If it all went to hell and I needed to hunt for survival, I could make a single box of rifle bullets last several years.   

       What I am is somebody who would be warm, dry, and well- fed long before the survivalist idiots figure out that a gun cannot provide shelter, first aid, or clean drinking water. For that matter, it can't even provide an edible meal, only the starting point for one.   

       // 6-8" deep, or just into a backstop? I would expect the depth to be relatively minimal, since most of bullet velocity is horizontal. //   

       In this case, the penetration was vertical because I was firing downward into a bucket, which is not a recommended practice, but it's not particularly dangerous if you wear PPE and know how to handle a weapon safely.
Alterother, Oct 30 2012
  

       Then, since most fire in combat is relatively level, I'd expect a bullet hitting ground (the only way they'd self plant) to cut a long groove, but not that deep of one.
MechE, Oct 30 2012
  

       Good point. I've never used a firearm in combat, and never will, and in my fervor to collect data for the betterment of mankind that detail escaped my notice.
Alterother, Oct 30 2012
  

       Forget about the heat, how many Gs are we expecting this little seed to survive? Several thousand I'd imagine. And not just once, but twice. First when you fire it and then when it lands in your unlucky planting medium.   

       Even if you have it encapsulated in something to keep the shell from deforming I'd imagine the parts inside the seed would get pretty well scrambled. Remember, shooting a seed inside a bullet is pretty much the same as shooting a seed with a bullet and it is a living thing after all. It might survive but I'd be surprised.   

       Ehh, I'm going to bun this anyway. WTF. I'm sure the problems could be worked out.
doctorremulac3, Oct 30 2012
  

       Not quite the same thing. The bullet accelerates over the entire length of the barrel when fired and decelerates through the length of however deep it goes into whatever it hits. Shooting a bullet AT the seed puts all the energy into crushing it the seed can withstand.
Voice, Oct 30 2012
  

       Pretty small difference from where the seed is concerned. It's still in for a pretty rough ride. But yes, I did say "pretty much" anticipating somebody pointing that out.   

       Like I've said many times though, we can put a man on the moon I'm sure we can put a chrysanthemum in our enemy's head.
doctorremulac3, Oct 30 2012
  

       Probably not- but there are a whole bunch of people here willing to give it their best shot ...
8th of 7, Oct 30 2012
  

       Maybe if we dip the chrysanthemum in liquid nitrogen and...
Alterother, Oct 30 2012
  

       Just fire some seeds and see if they germinate! Pop in a blank (or even a live) round, and stuff some wadding and seeds down the barrel. I'd guess that small and hard seeds would have the best chance of surviving.
spidermother, Oct 30 2012
  

       Okay, I'll unpack my handloading crap and try it. Stay tuned.
Alterother, Oct 30 2012
  

       Poppy or sesame seeds wrapped in a paper cylinder and packed into a 12-bore plaswad as as a sabot would have an excellent chance of surviving in a viable state; but the muzzle velocity is only about 300 m/s tops and the" range" is very short.   

       Seeds like that, along with coarse salt, have long been used for improvised low-lethality munitions.
8th of 7, Oct 31 2012
  

       Here's the blow-by-blow of my latest insomniac experiment:   

       1- find, unpack, and set up handloading crap.   

       2- load a tray of twenty .45 acp half-loads, each with six fresh red peppercorns (hardest seeds I can find in the middle of the night) packed between discs of die-cut wadding.   

       3- prepare six buckets, half-filled with sand, half potting soil. Arrange buckets on basement floor.   

       4- find, unpack, clean and assemble my old S&W .45, 'cause I really don't feel like firing peppercorn through my Kimber and Jenny's Defender is, well, Jenny's.   

       5- don full PPE including double eye protection.   

       6- fire one peppercorn round into each bucket. Note interesting sound and shower of loose soil.   

       7- go upstairs, explain to Jenny, calm dogs.   

       8- go back downstairs, sweep potting soil into pile, search for peppercorns. Five of 36 recovered, peices of several more. All others presumed KIA.   

       9- make .45 safe and report findings on Halfbakery over Kraken on the rocks. Watch several episodes of SeaLab 2021 while drinking more rum. Ponder what to do with 14 low-power peppercorn handloads.   

       Even with half-loads and protected by wadding, approximately 80% of my 'hard seeds' were blasted into itty-bitty pieces. Rest that on your case, M'lud.
Alterother, Oct 31 2012
  

       I stand in awe of your experimental initiative.   

       The questions are:   

       (1) Will the recovered 20% germinate?   

       (2) What is the germination rate of un-fired seeds?   

       (3) What happens to the seeds if they are embedded in gelatin in the rear of a hollowed-out bullet?   

       I note that there is a wide variety of shells which have complex timing and detonation circuits build into them. I'd expect that a dry seed should be nearly as robust as well-protected (presumably resin-potted) electronics. Prototype "smart bullets" (not shells, note) have been developed which include not only sensors but also micro- gyros.
MaxwellBuchanan, Oct 31 2012
  

       Gelatin (sensu lato) can be harder than glass or softer than jelly, and is biodegradable, so it does seem a good candidate. For that matter, what would happen if you simply shot people with rather firm, seed-filled gelatin rounds? They won't be armour piercing, but, as Mercutio said, 'tis not so deep as a well, nor so wide as a church-door; but 'tis enough, 'twill serve...' Although ironically, with his soul of lead, in his particular case, harder rounds would be indicated ... I'll get my coat.
spidermother, Oct 31 2012
  

       The rest is silence.   

       Thankfully.
8th of 7, Oct 31 2012
  

       … and saltpetre …   

       Right. Now we're getting somewhere …   

       There are two issues to resolve; the temperature of the projectile in flight, and the temperature after deceleration (impact) where more kinetic energy is converted to heat.   

       Critically, the duration of the peak temperature- akin to Pasteurization- needs to be established. Seed viability is destroyed when proteins in the germ are de-natured by heating.   

       Move over, Jamie and Adam- new Mythbusters comin' through!   

       We are now determined to get the facts on this one, even if it kills someone.
8th of 7, Oct 31 2012
  

       //I'd expect that a dry seed should be nearly as robust as well-protected (presumably resin-potted) electronics.//   

       I wouldn't. Electronics are prone to fail due to movement, not loading (compression). Most of the materials involved have fairly high strengths, the issue occurs if they slip. If they are potted, this can be essentially eliminated.   

       Seeds are prone to fail due to compression, with a relatively low material strength.
MechE, Oct 31 2012
  

       sp: //someone// -> everyone
lurch, Oct 31 2012
  

       // even if it kills someone //   

       Unlikely, but if I'm expected to continue my redneck science some schrapnel cuts are practically inevitable.   

       BTW, a 2 3/4" 12ga shell with a practice load and peppercorns loaded into one of those nifty Hornady stacking sabots results in finely ground pepper, a well- seasoned basement, and a sneezing fit.
Alterother, Oct 31 2012
  

       I hesitate to ask for even more of your time [Alterother] but I wonder if you could repeat the experiments with small seeds. I think they will perform much better than larger, hard ones because physics. First softer can mean tougher and second because of the square cube law
Voice, Oct 31 2012
  

       I have some thistle seed that we feed to goldfinches in the summer. I'm going to a Halloween party tonight, but I'll load some up tomorrow and try it. The main problem I'm encountering is that the muzzle blast from my .45 blows half of the soil out of the bucket, and that is the only caliber of handgun that I own. I'm thinking of repeating my surface heat and peppercorn-sowing tests with a .22 and a 5.56 (at a longer, more horizontalish range, obviously). That will probably take all weekend, but I have the free time because this is an insomnia week and my submission agency is currently under water.   

       There's something to be said for a wife who is not particularly concerned when woken by gunshots in the dead of night.
Alterother, Oct 31 2012
  

       I propose that in the interests of science we take up a collection to provide [Alterother] with an appropriate firearm to perform his testing with.   

       Have you any specifications we need to meet?
normzone, Oct 31 2012
  

       We-ell... In the interest of science, the perfect test platform would be the FN P90/R in 5.7mm with a heads-up reflex sight and a threaded barrel (for secure attachment of various scientific accoutrements, of course). If a collection is taken to purchase one, I will graciously accept custody of it... for science, naturally.
Alterother, Oct 31 2012
  

       I made up a tray of .45 half-loads each containing 8-10 thistle seeds wrapped in a wisp of cotton (from a surgical swab) and sandwiched between two wadding discs. This time, I stood on a stepladder and fired downward from approx 5' above the bucket, which considerably lessened the volume of soil displaced by the muzzle blast.   

       The thistle seeds mostly stayed wrapped up in the cotton, which made locating them surprisingly easy. Penetration was 1-3". Upon initial inspection, they seemed intact and unharmed, but under a microscope at 20x they appear a bit mashed and fragmented, though still whole (for control purposes, I based this upon comparison with unfired seeds from the same bag of bird food). I left two of the buckets (three shots each) unmolested and put them under my lights to see if the seeds germinate. I sowed a few unfired seeds at similar depths as a control group.   

       I am now working out how to conduct a horizontalish test using various rifle calibers. If results are favorable we will move on to germination testing.
Alterother, Nov 01 2012
  

       This is outstanding: serious experimentation to evaluate a halfbaked idea. I may purchase a spare cap, in order to be able to doff it to you, [alterother].   

       Two comments:
1) Are you sure the birdseed isn't treated to prevent germination? A lot of it is, to prevent spilled birdseed from weeding up your lawn.
MaxwellBuchanan, Nov 01 2012
  

       I'm not certain about that, although spilled birdseed does weed up what passes for our lawn. I'll check the bag; if it is treated in such a way, germination tests will require a trip to the hardware store in town.   

       What was the second comment?   

       As for any doff-worthy efforts on my part, the pleasure is all mine. The company that handles my submissions is, much like the rest of Hackensack, currently dealing with the aftermath of Sandy, and my bi-polar disorder has decided that I'm not allowed to sleep this month. Therefore, I currently have oodles of free time, and a man can only read andor write so many books before he has to go shoot something. Jenny is happy to see me handloading again, because she gets a little worried when I'm not engaging in high-risk activities and snowboarding season is a couple of weeks off yet.
Alterother, Nov 01 2012
  

       Excellent. This confirms the Buchanan family motto: "Nihil bonum fuit umquam peractae a bene libratum persona."   

       My second comment was going to be along the lines of gelatin-embedding of seeds. I would imagine that any derangement of the seeds results mainly from the fact that they start out fairly loose between the wadding discs; said discs will be slammed together abruptly upon detonation. However, there is only so much experimentation one halfbaker can be expected to do.   

       I doff my cap, if not to your experimentation, then instead to your current state of uppedness. If only there were some way to get all the bipolars in sync worldwide, we'd have the solar system fully explored and colonized in a week (although we might all then sit around the week after, wondering why bothered).
MaxwellBuchanan, Nov 01 2012
  

       Going to great lengths to get the answers to questions no sane person would ask - either that's being a halfbaker, or there's a clinical term for it.
lurch, Nov 01 2012
  

       //either... or//   

       Whence the mutual exclusivity?
MaxwellBuchanan, Nov 01 2012
  

       Formal request that [max] have no fewer than his full household staff line up and doff their caps
Voice, Nov 01 2012
  

       I will ensure that it is done. I will, however, need to wait until my chief assistant pyrotechnician has returned, and has had a short time in which to master his prosthetic elbow.
MaxwellBuchanan, Nov 01 2012
  

       All I'm doing is shooting at buckets of dirt, guys.   

       // Going to great lengths to get the answers to questions no sane person would ask //   

       Extremely [marked-for-tagline]
Alterother, Nov 01 2012
  

       //Aspidistra baby!//   

       [marked-for-award]
MaxwellBuchanan, Nov 03 2012
  

       Tests are ongoing.
Alterother, Nov 07 2012
  

       //tests are ongoing//   

       another tip of the hat for you sir.
Voice, Nov 07 2012
  

       Okay, here's what I've got:   

       Setting out to test seed planting via long arms rather than sidearms presented several obstacles. I moved my test range to the back yard, where I laid out three 4'x4' beds on a gentle slope, about 6" of used potting soil atop wet sand (the whole test area got quite wet at times, and some of it blew away). During test firing, I spread sheets of brown paper over the beds to track the path of my shots, since they would be coming in at roughly fifteen degrees to the horizontal plane of the bed surface.   

       It quickly became clear that I had no way to repeat my surface temp test, so I abandoned that step.   

       I started with the venerable .22 long, which for those non- gun nuts following the saga is a small, quiet rimfire round that your great-grandaddy used to hunt squirrels or rabbits or ocelots or whatever. My test platform was in fact my father's childhood squirrel rifle, a well-loved Winchester Scout. For the ammunition, I loaded two test trays of crimped 'blanks' with seeds embedded in the wadding (which I spray-painted Safety Orange for extraction purposes). The first tray consisted of red peppercorns (two per round, also painted orange), the second of thistles (6-9 per round, wrapped up in a little wisp of cotton that I dyed with a pink hi-liter). I also loaded a 'control tray', which consisted of empty wadding with the same charge, intended only to test excavation methods. I composed the powder charge on the light end of a normal .22 load.   

       I fired from a bench rest at a range of 15'. The peppercorn rounds had better ballistic and terminal performance, consistently settling at approx. 3" vertical depth. 25 out of the forty peppercorns fired were located and all appeared undamaged, though most had shed their inner calyx, which is part of the spice flavor but in my experience does not harm most seeds.   

       The thistle rounds I fired from 10', guessing (correctly) that the wadding and very light seeds would not fly straight. I recovered only seven of 20 payloads. Most of them contained only two or three seeds, but these appeared undamaged both to the naked eye and under magnification.   

       Next I stepped up to the 5.56 NATO, a high-velocity round used in the M16 assault rifle. My test platform was a Bushmaster AR-15 (a semi-automatic variant of the M16) with a 21" free-floating heavy barrel, a trusted rifle which I used in V-MATCH competition for many years. The first problem with this much more powerful round, which I anticipated, was that the wadding from blanks in that caliber is frequently blown into little pieces and never flies in a straight line. Nevertheless, I loaded up a tray of peppercorn rounds (three in each round, sandwiched as usual) and fired them from a range of 15'. 4 out of twenty hit the target, but I did not recover a single payload.   

       Going back to my basement, I used a leather punch to hollow out two wadding discs, glued them together, loaded two peppercorns into each and capped both ends with solid wadding discs, gluing the whole thing with CA glue and painting them orange. These I stuffed into half- load blanks and crimped them just enough to hold the payload in place. Loading each round into the chamber by hand, I fired from 15' and recovered 14 payloads. As I had hoped, most of my wadding cylinders split open on impact but still contained their payload. They completely penetrated the potting soil layer and burrowed into the sand below, to a vertical depth of 7"-9". A few of the peppercorns split or crumbled, but most appeared unscathed.   

       I repeated this technique with the thistle seeds, recovering 16 of 20 rounds fired. This time the delicate seeds remained intact but were obviously damaged by the extreme forces incurred in firing. A small number of them appeared viable, although the hulls still exhibited the 'mashed' appearance under the microscope.   

       Just out of curiousity, I loaded a tray of 6.8mm spc, 10 peppercorn and 10 thistle. The resulting massacre does not warrant reporting.   

       Make of this what you will. Unless anyone has a fresh idea, I think I'm done.
Alterother, Nov 08 2012
  

       [MB], the thistle seeds I've been using are indeed the non- growing kind. I've just returned from the hardware store, where I picked up a packet of wildflower seeds for viability testing. I plan to load them in .45 brass and sow them using the bucket method, which I will then place in my grow room alongside a hand-sown control group.   

       I'm busy again, but I'm still not sleeping much, so I'll probably load and fire the rounds tonight. Germination should take less than a week.
Alterother, Nov 08 2012
  

       You know, this ought to be published somewhere. Possibly as evidence. But certainly published.   

       So, are we awaiting sprouting news from The Germinator?
MaxwellBuchanan, Nov 08 2012
  

       Storebought peppercorns generally won't sprout anyway.   

       I would be curious about the other.
MechE, Nov 08 2012
  

       See above.   

       I wasn't counting on the peppercorns to sprout; they served as a stand-in for hard and durable seeds, used for the sowing tests. The thistle seeds were leftover bird food, which Lord Buchanan correctly observed had been sterilized in order to not make a mess of weeds under the bird feeder.   

       The results of my germination tests using storebought wildflower seeds will be published within a week or so. The control group will definitely sprout (if a plant won't grow under my lights, it won't grow anywhere), so we'll have a solid comparison to the viability of the handgun- sown group.
Alterother, Nov 08 2012
  

       There's a small business for you. I'll buy your custom handloads. Probably have to ship you some of our natives so as not to introduce non-native species in our few remaining rural shooting ranges.
normzone, Nov 08 2012
  

       This is outstanding. There should be a HalfBakery Award for Experimental Recklessnessness, and I nominate [Alterother].
MaxwellBuchanan, Nov 08 2012
  

       Please, you're all too kind. It's not about me, it's about the 'Bakery. Also, I was bored.   

       I'll take the award just the same.
Alterother, Nov 08 2012
  

       I disapprove the nomination, and move to rescind it.   

       [Alterother] is a trained professional, with adequate experience in the field such that reduces the risk to so low a level as to eliminate the element of recklessness.   

       However, I'm willing to concede that his actions warrant a Meritorious Conduct for being arsed to follow up on something.   

       (Sorry, [Alterother], but I didn't want them to confuse loading and firing weaponry at home with recklessness. You know how the unarmed can become confused over simple verbiage)
normzone, Nov 08 2012
  

       I think you'd have to ask the seeds about the recklessness of this undertaking. I'm pretty sure it's not entirely reckfull from an earthworm's perspective either.
MaxwellBuchanan, Nov 08 2012
  

       The only professional training I've had is as a welder, [norm]. My firearms knowledge is all self-taught or the result of casual mentorship. I don't even go so far as to call myself an expert, so don't try to rain on my parade by pointing out that I sort of know what I'm doing.
Alterother, Nov 08 2012
  

       Well, in the face of this testimony I must reluctantly withdraw my previous objection. Although the nominee does appear to be undervaluing himself at this moment, his statements allow me to endorse the nomination as previously submitted.   

       Let me know when the parade is scheduled - can we do it when the weather is nice?
normzone, Nov 08 2012
  

       I wonder if the big explodey rockets (fireworks) could be made to disperse seeds? Or (if you really don't like any of your neighbours) kudzu cuttings.
MaxwellBuchanan, Nov 08 2012
  

       If you can eject a parachute you can eject seeds.
spidermother, Nov 08 2012
  

       Fireworks should be much simpler than bullets. The forces and heating (except for the bit that is actually burning/exploding) are much lower. Put the seeds to the outside of the warhead so they're ejected before the sparks ignite, and it should work fine.
MechE, Nov 08 2012
  

       //Fireworks should be much simpler than bullets.//   

       My thoughts exactly. See my first Halfbakery posting [link].
csea, Nov 08 2012
  

       Germination study underway. I'm going out of town next week, so my results will be published sometime after the 18th.
Alterother, Nov 09 2012
  

       Excellent - the 18th it is. I'm mildly surprised that the sentence was so short.
MaxwellBuchanan, Nov 10 2012
  

       I got home earlier than expected. The control group is flourishing. The test group has yet to germinate.
Alterother, Nov 16 2012
  

       I'm sorry to hear that.
Voice, Nov 16 2012
  

       Excellent work [Alter]   

       //I'm mildly surprised that the sentence was so short// The first sentence was only 3 words but the second was 17 words.
AusCan531, Nov 16 2012
  

       I'm declaring this myth bus... Oh, wait, wrong site.
MechE, Nov 16 2012
  

       Just to make sure, I dug up the seeds from the test group a few minutes ago and I actually found two (out of approx. 60 seeds 'sown' in 9 shots) that had begun the first phase of germination, but they were withered and I doubt very much if they were metabolizing properly. Still, that's something.   

       A few others had pushed out of their calyxes/hulls, but that's not a sure sign of germination, as it is simply a matter of expansion as the planted seed absorbs moisture.
Alterother, Nov 16 2012
  

       This idea is currently No 1 on Reddit. [link]
AusCan531, Mar 08 2014
  

       They should be paying me for all the preliminary research.
Alterother, Mar 08 2014
  

       Try your luck [Alterother]. [link]
AusCan531, Mar 09 2014
  

       You could pack your fruit pips into bullets to be planted this way. Eats, shoots and leaves.
MaxwellBuchanan, Mar 09 2014
  

       Did a search of "how hot is a bullet after it's fired" hoping to find an answer in the form of a number. 300 degrees F, 200 C, or the like. Wow, wow, wow. I previously posted a thinly veiled rant about what I call "squidding", that is, the posting of long winded non-answers on question forums like Yahoo Answers. (squids squirt gobs of obscuring ink, hence the analogy to typing lots of words that say nothing.)   

       I have never, never, never found a question that requires a number for an answer being answered with such squidding. Here's some of the DOZENS of people without a clue as to how hot a bullet is after it's fired sharing their scintillating insight anyway:   

       Non-answer #1: "This is a complicated question due to the number of factors that would contribute to a transfer of heat energy. Furthermore, you would have to specify a projectile and powder charge and a given barrel length and ambient temperature readings for every case."   

       Non-answer#2: "how hot do the following bullets calibers get when they are flying thought the air... " They are already hot. Flying thru the air cools them off a tad."   

       Non-answer#3: "Powder ignites hot enough to destroy barrel steel, for a moment. But that only lasts for a few milliseconds. Someone better at physics should answer that"   

       Anyway, after much sifting through this kind of blather, I found somebody who said about 500 degrees F who said they had read about measurements being made with actual mesaurement devices. Sounds about right.
doctorremulac3, Mar 09 2014
  

       I can believe that the *surface* temperature of the bullet is extremely high, but not the core temperature.   

       Clearly, the outside of the bullet isn't hot enough to melt, otherwise those nice guys at CSI wouldn't be able to do all that clever stuff.   

       So, if the bullet is made of lead (are they still?), its surface temperature when it leaves the barrel must be at most 330°C (600°F).   

       I'm assuming it spends maybe 1msec in the barrel.   

       So, if you heat the outside of a bullet to 330°C for one thousandth of a second, how hot does does the middle get?   

       Answer - not very.   

       So yes, the outside of bullet is very hot when it leaves the gun, and the inside (the great majority of the bullet by mass) will be at ambient. The mass-average temperature will be something like warm.   

       On impact with a solid, hard target, however, the bullet's kinetic energy (about 0.5kJ) will be converted mostly into heat as the bullet deforms. If this 0.5kJ is spread evenly throughout the bullet's mass, given a heat capacity of about 4J/g/ °C for lead, it will raise the bullet's temperature by about 60°C. This assumes a bullet velocity of 300m/s. If the velocity is twice that, the temperature increase on impact will be about 240°C.
MaxwellBuchanan, Mar 09 2014
  

       I'll just throw in that lead is an excellent conductor of heat. I'll leave out that bullets aren't all made of lead these days.
doctorremulac3, Mar 09 2014
  

       // Powder ignites hot enough to destroy barrel steel, for a moment. But that only lasts for a few milliseconds //   

       The boundless stupidity of that statement speaks volumes about the evolving human condition.
Alterother, Mar 09 2014
  

       How did I miss all this fun back in 2012? What a fine mix. My favorite: /If you use a cast lead bullet in a .17 Remington (very small mass, not a really good ballistic coefficient) and pump up the velocity to higher-than-reasonable levels (say, 4200 fps) you can get a situation where the bullet will vanish (melted, then torn apart by centripetal force) before it gets to a target 100 yards away./   

       What a great SF short story this principle would make. I am a little concerned that liquefied droplets from the original bullet might still impact on the target, which would be stingy.
bungston, Mar 09 2014
  

       I'm not sure what was meant by "ballistic coefficient," but 'ballistic profile' is a term often bandied about when discussing cartridge performance, and the .17 HMR is considered to have a pretty good one. On a windless day my 77/17 shoots flat as a pan out to around 200 yds.   

       As for the bullet tearing itself apart at 4200 fps...I can't disprove it, but I'll only believe it when I see it happen.
Alterother, Mar 09 2014
  

       //I'll just throw in that lead is an excellent conductor of heat. I'll leave out that bullets aren't all made of lead these days.//   

       I don't think that affects the argument much. The point is that lead bullets (even though lead may not be used nowadays) survive without significant meltage of the outer surface.   

       That tells you that the surface of the bullet isn't heated to more than 330°C. Change the metal of the bullet and, give or take, its surface temperature on leaving the barrel won't be that much different.   

       So, regardless of the bullet material, its surface is heated to a few hundred °C over a period of a millisecond. Even for a very good thermal conductor, I'll put money on the fact that if you heat the surface for one millisecond, the vast majority of the interior will still be at ambient.   

       To take a very simple example, hold a few-inch piece of copper pipe in a gas flame. How long before it becomes hot in your hand? A few seconds? A second? Not less than a second. That's how long it takes heat to travel a few inches in a good conductor. So how far does heat travel in 1/1000th of a second? And so, how hot is the inside of the bullet as it leaves the muzzle? It's at ambient.
MaxwellBuchanan, Mar 09 2014
  

       If *all* of the kinetic energy of 10g bullet starting at 300m/s is converted into heat, and if *all* of this heat ends up in the bullet rather than the air, that will raise its temperature by about 50°C.   

       I suspect that the correct value for *all* is <0.25 in each case.
MaxwellBuchanan, Mar 09 2014
  

       Bear in mind also that bullets are* designed to minimize air resistance. The really good ones are made in a style called 'boat-tailed'** that create a slipstream and a stable wake, eliminating a great deal of the turbulence that can build up behind a bullet as it flies.   

       * and have been for last 150 years or so   

       ** because the rear of the bullet is slightly tapered rather than squared off, giving it a shape resembling the bird's-eye profile of a sleek watercraft
Alterother, Mar 09 2014
  

       [Alterother] - about the melting .17 bullets - I'll admit that I wasn't an eyewitness. It's something I'd heard from my pa, about the times when he was knocking about with P.O. Ackley. (He being the creator of the "Ackley Improved" wildcat calibers, which you can find readily on-line; particularly see the ".17 Ackley Bee". [I had a Ruger M77 .257 Ackley Improved he custom made for me. Traded it off to Pa for a .222 Remington Sako Vixen and a Honda 360. I was young and dumb])   

       Anyway, when they were doing a lot of testing, they found they could save a few pennies by adding plumber's solder - the kind you could get in the 1 lb bars - to their lead pot, and throwing in some wheel weights. The plumber's solder was a 50/50 lead-tin mix; the wheel weights were 95% lead, with about 3% antimony and 2% tin. So they didn't have a really high precision alloy, but they tried to get close to 90% lead (for the density), 8% tin (for lowering the melting point), and 2% antimony (to make the bullets harder, to resist deforming when pushed into the cartridge neck).   

       Anyway, if you run the numbers, a 20 grain bullet (that's about 1.3 grams) travelling 4200 fps (that's 1280 m/sec) has a kinetic energy of about 1062 joules. The exact heat capacity of their alloy would be hard to pinpoint, but would be in the range from 0.15 to 0.24 joules/(gram Kelvin); I'll go middling for 0.2 j/(g K).   

       That means 1 joule of energy would suffice to raise the temperature of 1 gram of bullet by 5 Kelvins. It would raise 1.3 grams by 3.85 Kelvin; 1062 joules would be enough to (theoretically) raise 1.3 grams of that alloy by 4085 Kelvins.   

       The eutectic point (that's not exactly a "melting" point, but a point at which the alloy partially liquifies, leaving it with zero tensile strength) of the lead-tin solder is about 183 degrees C. That's about 160 K from ambient. So, yes, the numbers bear it out.   

       (Also, the bullet molds they used were not boat- tailed - they were more of a semi-wadcutter design, to make a compact bullet that wouldn't take up as much space in the cartridge neck, making more room for powder. They were looking for maximum muzzle velocity at the time, trying to get a bullet above 5000 fps. by any trick possible. Downrange performance wasn't part of the project.)
lurch, Mar 09 2014
  

       All of that makes sense, but I'm still skeptical about the mid-air disintegration. Disintegrating upon impact, absolutely--even pellets out of my Tech Force (an impressive Chinese-built air rifle, for the uninitiated) liquify against a steel target. Also, my own hot load experiments have shown me that any bullet under 33 grains will destabilize at around 3000 fps regardless of caliber (I even necked some .22 shorts into 5.56 brass one time, with predictable results). I haven't been able to get anything heavier moving that fast. As far as ballistic science goes I'm a weekend dabbler at best, so maybe someone else has better data.
Alterother, Mar 10 2014
  

       ^Perhaps you need more of a twist ? give it more spinny properties.
FlyingToaster, Mar 10 2014
  

       If you give it more rotation than 1:5 the bullet likely won't even make it out of the barrel. Almost all of the resistance a bullet encounters after firing (but before impact) is from contact with the lands.
Alterother, Mar 10 2014
  

       There's probably an optimum rotational energy, given weight and dimensions, to poke through the air without tumbling. Firing two identical-sized bullets out of the same firearm, the heavier one will have more RE.   

       soo.... .22LR hollow-point ? rather than a Short.
FlyingToaster, Mar 10 2014
  

       Based on casual knowledge of military and hunting long arms I'd say the rotational sweet spot is somewhere around 1:9. I don't know as much about sidearms where I could guess at the average twist ratio.
Alterother, Mar 10 2014
  

       //Change the metal of the bullet and, give or take, its surface temperature on leaving the barrel won't be that much different.//   

       This probably isn't true. Remember that the bullet is deformed during firing, and is experiencing friction in the barrel. The energy it takes to do that to brass is going to be higher than for lead, and even higher for some other materials.
MechE, Mar 10 2014
  

       Copper has been the jacketing material of choice for over a century. Gotta be a good reason for that.
Alterother, Mar 11 2014
  

       Is it copper? Not brass? Or does brass count as copper. Good looking gussied up copper?
bungston, Mar 11 2014
  

       Nope, copper. Once in a while you find something jacketed in a proprietary copper alloy (such as Speer Gold-Dot hollow points or the infamous and long-discontinued Black Talon), but nearly all jacketed rounds are and always have been made with copper.
Alterother, Mar 11 2014
  

       Military puts copper jackets on the lead bullets. I think copper is a bit more squishy, like lead, than brass. Nothing to do with the shell casing which is pretty well always brass.
FlyingToaster, Mar 11 2014
  

       There is a trend towards all-copper ammunition for hunting, in an effort to reduce the amount of lead finding it's way into harvested meat and animals that consume gut piles from same.   

       This trend could pose a heating challenge to the goal of seed planting via firearms - alternate materials may be required.
normzone, Mar 11 2014
  

       Really ? I thought copper-jacketed rounds were banned from hunting.
FlyingToaster, Mar 11 2014
  

       Maybe in Canadia, although I can't imagine why. Nosler- tipped rounds (a fancy form of hollow point, essentially) have become the standard choice for deer hunters, with good reason, and the design would not be possible without a copper jacket.   

       I know that hunting with full metal jacket rounds has been banned in some places because of the blow-through issue, but the soft tips and hollow points used instead are still copper jacketed.
Alterother, Mar 11 2014
  

       //weekend dabbler// I've shot .22 "Accelerators": saboted round in a .308 cartridge. (IIRC) flat trajectory out to 300m then drops like a rock (which'd be when it starts tumbling). Wikipedia says >4kfps for the .30-06 version... that's 55gr though.
FlyingToaster, Mar 16 2014
  

       Interesting that it flies straight until a certain point--most bullets I've seen destabilize (free of external influence) do so almost immediately. You can tell by watching the "bullet trail" through a scope; a true shot almost looks like somebody drew a straight line in the air with a pencil, while a tumbler looks like heat mirage in the wash of a jet engine. I've never seen one go straight and then tumble.   

       I wonder if there's a physics foible which causes a bullet that would fly true at 2000 fps to violently destabilize as it slows from twice that speed. Maybe it's to do with air density and resistance effect on a spinning object, or if the Accelerator .22 really does cause the round to deform as [lurch] describes.
Alterother, Mar 17 2014
  

       The gyroscope effect is what keeps the bullet from tumbling in the air soup it's pushing its way through.   

       Assuming that, when the forward velocity is halved, the spin velocity is also halved (which it probably won't be, exactly, but whatever), then the halved original aerodrag is being battled by only a quarter the original gyroscopic effect (RE = ½mv²).   

       [edit: ah you're talking about something else'ish...]
FlyingToaster, Mar 17 2014
  

       The US military is now trying to make this idea come to (heh) fruition. Linky
Voice, Jan 09 2017
  

       The selection of seeds is quite specific to the area/conditions to where they will be planted. I could see the logistical issues getting out of hand here: "Bloody Supply! They sent us sent us ammunition requiring cool summers with plenty of rainfall shells when we're mobilizing tomorrow to the Middle East again." Meanwhile, the cacti and succulents are deployed into Scandinavia for the 'Operation Winter Shield' exercise.
AusCan531, Jan 09 2017
  
      
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