Firstly, a story that was told to my DH by his Dad. Sometime ago in America a policeman commited a murder using his service revolver. He then spent many hours and days at the range 'pracitising'. In fact what he was doing was wearing away the rifling so that when the ballistics tests were done, the bullet no longer matched the rifling.

Second one. Is it possible to reuse a fired bullet on a newly constructed round, so that it could be fired from a different gun? If it were possible, would the rifling marks on the bullet be a combination from both guns or would the rifling from the second gun be worn over the top of the first? Or is it just not possible to recover a fired bullet to reuse, no matter what you shot into the first time?

bws,

quote:

Originally posted by OneProudMomma:
Firstly, a story that was told to my DH by his Dad. Sometime ago in America a policeman commited a murder using his service revolver. He then spent many hours and days at the range 'pracitising'. In fact what he was doing was wearing away the rifling so that when the ballistics tests were done, the bullet no longer matched the rifling.

Second one. Is it possible to reuse a fired bullet on a newly constructed round, so that it could be fired from a different gun? If it were possible, would the rifling marks on the bullet be a combination from both guns or would the rifling from the second gun be worn over the top of the first? Or is it just not possible to recover a fired bullet to reuse, no matter what you shot into the first time?

bws,

I suspect Jd Shootist will have an awful lot too say on this one, but I'm pretty sure that if you shot a non-expanding bullet into water, and it didn't break up, you could shoot it from a different gun. I'd also asume that the rifling would be a compound of the two guns.

Oh dear, Welsh Boyo, apparently my reputation precedes me! Always happy to oblige, however!

OK, to deal with One Proud Momma's questions in order.

1. It is theoretically possible to "wear away" the rifling of a barrel by repeated use. Ballistics evidence for court purposes falls into two forms. It is possible to identify the make & manufacture of a weapon by certain standard features of the gun barrel - the rate of twist of the rifling, the exact diameter of the lands and grooves of the barrel, (for example a Colt in .38 Special will measure .355 inches internal diameter, a Smith & Wesson in .38 Special usually measures either .356 or .357 inches, according to the model,) - and also the number and width of the grooves. These features will still be identifiable over many, many tens of thousands of rounds - by the time they're gone, the gun will be unusable. The other form is obtained by firing a bullet of the same type, from the suspected weapon, into a water barrel which catches it, undamaged, then comparing it with a bullet recovered from the crime scene under a microscope. Dirt, damage & small scratches will leave "tracks" along the sides of the bullet, so-called "jump bulges" will be visible as rings near the front of the bullet, caused by the motion of the bullet as it is forced into the rifling on firing compressing it slightly and, believe it or not, even the base of the bullet will show marks caused by the pressure wave behind the bullet as it leaves the muzzle - these marks will vary according to the exact shape of the muzzle "crown" and any damage at the crown will leave identical marks on the base of the bullet. Similarities in bullet markings can be demonstrated in court by use of blow-up photographs. A good ballistician will be able to identify similarities between bullets fired several hundred rounds apart - and indeed, will be able to make a pretty good guess at how many rounds were fired in between two bullets as well! Eventually, however, enough wear in the barrel will create enough changes in the bullet markings to prevent accurate comparison. However, your mythical Police Officer would have to fire many hundreds of rounds through the weapon to achieve this - so I have to confess to being ever so slightly doubtful...?

2. If you managed to follow the above, you will realise that the water barrel recovers bullets in a fired, but undamged state. They would, in theory, be re-usable in another round. However, bullets, even copper-jacketed ones, are surprisingly malleable under the pressure and heat of firing - the marks left by the first firing would be almost completely erased and replaced by those from the second firing - the gun used for the first firing would be unidentifiable, but the gun used for the second firing would be clearly identifiable. However, the fact that the bullet had been fired twice would also be identifiable - so breaking into the ballistics locker and refiring a recovered projectile through a different gun would not neccesarily work - it would be immediatly obvious on testing that it had been fired twice, and the second gun would be clearly identifiable - so if your mythical policeman's access to the second gun could be demonstrated, he could still be caught!

Whew - OK, breathe out now....

Surely it would be much easier to insert a metal bar into the barrel of the gun and stratch so badly that the grooves are completely different. I don't know if this is stupid, but it seems like a much quicker way to get the same result as firing a gun over and over again.

Yes, indeed, there are many ways of altering the barrel profile, sufficiently to make ballistic comparison impossible. However, the "brute force" method you suggest has its problems. The gun would almost certainly be unfirable afterwards - and potentially very dangerous to the shooter, if he tried; (remember, in the Example OPM cites, this is a Police Officer's service revolver - he still has to carry it on duty afterwards - it would automatically arouse suspicion if he disposed of it.) However, although unfirable, such a damaged gun could still be "slugged" by a ballistician, (drawing a lead slug through the barrel, using a wire to pull it through - can even be done on a comprehensively bent barrel,) which would reveal the same marks and striations as would be seen on firing - therefore it would still be identifiable. If you attempted to "file away" the inside of the barrel, you would destroy its evidentiary properties, sure, but the damage would be immediately obvious and tell-tale - thus arousing suspicion - you could not pass it off as "wear and tear." The oddest one I have heard of, was re-rifling a barrel. Someone trying to hide evidence of culpability, took his gun to a gunsmith's shop and rebored his gun on a "button rifling" machine - the original, (Colt) barrel was .451 and he took it out to .455 inch. Problem was, his 9-year-old gun now had brand-new "unfired" rifling, in the wrong size for that manufacturer - it was promptly tested, and, although the bullets could not be compared, marks on the fired cartridge case were compared - surprise, surprise, the primer indentations and extraction marks on the cases were found to be identical!

The only story I've ever heard, (apocryphal, so also possibly mythical,) which sounds possible, was the NY Police Officer, who was also a hit-man for the mob in his spare time. He had a reputation within the NYPD as a fanatical shooter, carried a 9mm automatic pistol on duty, hit the practice range at least three times a week, and requested a new barrel for his sidearm at least once every six months, because the other one was "shot-through." Although his sidearm was tested at least twice, it never "matched" with bullets recovered from crime-scenes. As you've probably guessed, although the old, replaced barrels were supposed to have been destroyed, he had managed to obtain one, which he swapped into his gun every time he used it for something illegal, then swapped out again before returning to work. He must have had a great hiding place for his spare barrel, though, because, supposedly, the investigating officers were convinced he was the hitman, and even thought they new how he was doing it, but could never find the "extra" barrel to prove it.