Ballisitic Testing/Matching

I also found this:
http://www.nij.gov/training/firearms-training/index.htm
Click to expand...
That doesn't appear to be the best source.

There are many incorrect, unclear, or obscure statements in that text. For example (discussing patched and unpatched round balls being fired in rifled and unrifled bores):
www.nij.gov said:
In theory, a sphere should travel through air equally well with or without spin stabilization. In practice, as soon as the propellant’s pressure wave acts upon the soft lead ball, it is deformed into a stubby cylinder. In-bore deformation of a projectile by firing pressure is called slugging. By their nature, cylinders require artificial stability; this is provided by the spin imparted by rifling.
Click to expand...
(emphasis mine)
It's so wrong, I don't even know where to start. I'm hoping the author simply confused the concepts of obturation and bore slugging. -But failing to understand the differences between those concepts brings doubt as to the author's real "expertise".


However, it does cover the general principles of inspection. As most people might assume, they are simply looking for any microscopic detail that might be present on all (or most) cartridges and/or bullets from a specific firearm/magazine.
A good example is found here: http://www.nij.gov/training/firearms-training/module09/fir_m09_t07_03.htm

And, challenges that might be encountered are discussed a bit, as well.
One statement caught my eye:
www.nij.gov said:
Ultrasmooth machining techniques: In many cases involving highly polished surfaces, there may be no marks of value present for comparison purposes. This is frequently noted in new firing pins and in some brands of firearms.
Click to expand...

So, maybe the short answer to rendering a firearm unidentifiable is just to polish everything....
 
I really enjoyed reading through your link raftman. Of course it will have some bias, seeing as he has an obvious agenda, but found it had a lot of interesting info.
 
bullets are matched to a specific barrel, and can also be matched to a specific gun brand (sometimes).

the firing pin also leaves identifying marks on the primer unique to each gun.
 
New York's cateloging of fired shells

New York and Maryland has had a system in place for some time of collecting and cataloging spent shells as part of the requirments for purchasing a firearm. From the Washington Post:

"One of the left’s favorite gimmicks is requiring every gun purchased to be test-fired so that shell casings can be “fingerprinted” and entered into a database for use in forensic investigations. New York state has had such a requirement for more than 10 years. So far, the Combined Ballistic Identification System has cost $40 million, used at least 200,000 police man-hours and cataloged 311,859 casings. Not one crime has been solved because of the system, according to the New York State Rifle & Pistol Association. In 2004, the Maryland State Police concluded, “There have been no crime investigations that have been enhanced or expedited through the use of” Maryland’s Integrated Ballistics Identification System"

http://www.washingtontimes.com/news...ire/?sms_ss=facebook&at_xt=4dc6bbf72523814e,0
 
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