You’re correct. Steel jackets will sometimes strike sparks off rocks or steel backstops. This has been known to ignite grass fires on outdoor ranges under dry conditions. If you’ve ever swept an indoor range, the floor is covered with a surprising amount of unburned powder. Sparks, with enough bad luck, could ignite this. While it won’t explode, it is a fire hazard. On the indoor ranges, though, it is mostly that they are unnecessarily hard on the steel back plates.
Also some more savvy don’t like 7.62x25mm for the same reason. BTW great visual website on bullet penetration there. The tl;dr here is that this pistol round (also used in SMGs, but that says nothing about performance) penetrates similarly to rifles. It’s not great stopping power though supposedly, as it’s mostly FMJ and not terribly heavy.
Full text pdf. here. They helpfully list wound profiles and permanent wound cavity measurements too. Important quotes not listed in engineer_comp_geek’s quoted abstract are as follows:
I wasn’t able to find a figure for permanent tract diameters after 15 cm within the gelatin and I am wondering whether that depth of penetration was where the 30-cal rifle bullet began seriously tumbling and causing a wider cavity? Anyway, for MV in the 1850 fps range, my understanding is that temporary cavitation, especially without accompanying projectile fragmentation, is not correlated with increased tissue damage, except perhaps in low shear-resistant tissues, such as found in the brain or liver. (Distinguished from the situation where MVs exceed 2200-2500 fps, especially when the projectile fragments. Here, the temporary wound cavity may lead to destroyed tissue—see ‘shocked meat’ in a deer hunting context—or the roughly spherical wound volumefrom a fragmenting high speed 5.56 mm bullet.) For lower speed projectiles like the study’s or for nearly all handguns, permanent wound cavity is what is needed, and it turns out the musket provides a much larger one for the study in question.
Aside, the gelatin blocks they used must have been massive; I’m not familiar with seeing 100 cm wound tracks in terminal ballistics papers. Mainly because, unless you’re shooting large game, the bullet’s already penetrated through the target well before 100 cm is reached.
As to the OP, bullet construction plays a role in answering the question. Handgun bullets are similar to the bullets in the cited study in that permanent wound cavity size directly correlates to their effectiveness. Bullets driven too fast for their construction, e.g., a 115 gr. 9mm bullet fired instead from a .357 SiG or a 9x25, may fragment and fail to penetrate the desired 12 inches in ballistic media. The same bullet, driven several hundred fps slower, will better maintain its integrity and keep the sectional density Stranger mentioned, and therefore penetrate further than the fragmented bullet. The further it penetrates, the more likely it is that the target will have two (or more) holes to leak blood out of rather than one. Ceteris paribus, the more holes, the faster the target will exsanguinate, and the faster the target will be stopped or die. Balanced against the threat that the bullet will continue through the target and hit something you don’t want hit, of course.
Google books has the Report of a Series of Experiments Conducted at Frankfort Arsenal In Connection with the Ordnance Department of the US Army. Report to the Surgeon General for the Secretary of War., by Capt. L.A. LaGarde, cited in both the musket study and this Fackler survey of historical attempts and papers to quantify wound ballistics. The report is from pages 73-95, and has quite a bit of data, including photos of the recovered projectiles and cadaver femurs.
Every last poster in this thread seems to have forgotten a basic rule of thumb for empirical science.
Only change one variable at a time!
For this thread’s topic to be accurate, if you take exactly the same bullet and add or remove some gunpowder, what does this do to lethality?
I suspect that when you only change this variable and no others, more gunpowder is always better on average. (well, til the gun explodes on you I suppose)
The same bullet would probably do even better if you fired it from a hypersonic gas gun or some kind of electromagnetic launcher.
You suspect wrongly. Real life bullets vary in construction and purpose. They are designed to accomplish particular goals and function best within certain velocity parameters. Plain lead bullets, if driven too fast, tend to strip out of the rifling. This leads up the bore and gives erratic bullet flight. Lightly constructed jacketed hollow point or soft pont bullets, i.e. varmint bullets, will literally fly apart on exiting the barrel if driven too fast. There can also be issues with bullets in general losing penetration at extreme speeds because they shatter on striking the target.
Wildcatters have been playing with this kind of idea for a century or so. The physics equations are useful but they aren’t the whole story.
When I said “til the gun blows up”, I meant “til something breaks”. Again, repeating my statement : there’s a certain amount of gunpowder that is the maximum a given bullet and/or gun design can tolerate. You can also use less than that. Between the maximum and zero gunpowder, I predict that maximum gunpowder always does the most damage on average.
A bullet that shatters upon striking the target probably does even more damage because it’s broken into smaller lethal fragments.
After looking at the links that Gray Ghost posted I have some doubts about this.
The one thing you see in those links is that the higher velocity rounds produce a very narrow wound cavity for some distance, and only after the round has penetrated pretty far does the wound cavity start to expand. The slower rounds, on the other hand, produce a wider wound cavity right from the start. In those links they admittedly aren’t comparing apples to apples. The high velocity rounds and the slow velocity rounds aren’t the same rounds. But I think in general the same thing applies even when using the same round. As you slow the round down, the larger part of the wound cavity is going to get closer to the wound entrance. With less energy, I think the wound cavity is also going to get smaller in general at the same time. So there’s probably some optimal point where the reduction in wound cavity size due to the reduced kinetic energy will balance out pulling the largest part of the wound cavity closer to the point of entry.
A bullet that shatters makes ugly, but superficial, wounds. Retaining mass while still expanding has been the focus of hunting bullet development for about a century now, too. Your suppositions have been supposed before and discarded because they did not play out as supposed in the field. Firearms are aa mature technology and there isn’t a lot that hasn’t been tried.