| From: | Sommers sommers@*****.edu |
|---|---|
| Subject: | Gun Disposal |
| Date: | Wed, 11 Aug 1999 14:52:48 -0400 |
>This kinda made me start thinking. How hard is it to ID a gun by just
>the bullet. I know you can determine if two bullets were shot from the
>same gun, but I mean, "The victim was killed by a 9MM. Ballistic says
>it looks like it came from a _______."
>
>Mockingbird
Each barrel has its own particular kind of barrel wear, which imparts marks
on the bullet as it leaves the chamber and exits the weapon. If you take 2
Glock 17 pistols and fire them, the bullets will have different marks on
them due to slight differences in machining, wear-and-tear on the weapon, etc.
However, if those Glock were manufactured at the same time in the same
plant, they likely went through the same set of machines to make them. The
machines that make the barrels and the rifling in them all do the same job,
and will leave marks that are very similar.
So when ballistics looks at the bullet, they can find 5 grooves on the
bullet that were left by a 60% helical twist (or whatever that barrel is).
They check their database and find that Glock 17's are made with that kind
of rifling. They often can further refine it (if they have had samples to
compare to) that the manufacturing of Lot X from Stuttgart leaves an extra
1/8 inch turn on the last groove.
So the ballistics boys can tell that the murder weapon was a 9mm Glock from
a lot that was made 3 years ago, sold to a distributor in New York, and
stolen from the warehouse 2 years ago. If they actually get the weapon,
they can then do further comparisons.
Sommers
Insert witty quote here.
