bullet evidence

[Nicodemus38]

might be a repost, the site is wacky tonight for me.



if a bullet moving at any velocity and impacts water, or a feather pillow, is considered absolutely worthless by gunsmiths for the practice of slugging a barrel.

then how can the fired bullet be 1. measured and given a caliber 2. be used to compare to a bullet fired from a test shot in the lab into water tank?

heres logic loop

1. impact deforms bullet beyond what the barrels bore is, thus it is not gong to give correct measurement of the bore

2. if bullets deform differently from shot to shot, and differently in different material how can a bullet pulled from say a log be compared to a bullet that was shot into a water tank?

 

[CapnMac]

I don't work in a ballistics lab, nor know any who do; not even playing an expert on the intertubes, either.

From observing my collection of recovered spent rounds, for most of them, the base tends to stay near the before-firing diameter.

But, after that, I don't know squat. Like how a lab would know a 147gr ground was from a 9mm or a 38spl or 357mag. And, that presumes that most of that 147gr is still "there".

Telling these things from just a recovered round seems a bit more 'tv' CSI than IRL.

 

[mgkdrgn]

When you slug a barrel you are looking to learn the EXACT diameter of the bore.

When doing a CSI comparison of one bullet to another for a match, your only real concern is the markings on that said bullet. For bullets with -very- similar bore diameters, they might not know the exact caliber of the gun.

For example, I have some 150gr (or there abouts) lead bullets that are meant to be used in 45 ACP, but for punching holes in paper at close range I'll wager they will work just as well out of a 45 Colt cartridge. I wouldn't know for sure what they came out of until I match a slug to a sample fired from a known gun. (and I'd also be willing to bet that for a 150 gr semi wad cutter, they would be looking for a 45 Auto and not a 45 Colt revolver, unless the land/grove count/twist rate gives it away)