TexasCHLforum.com

Theoretically, "ballistic fingerprinting" COULD work. Each gun's chamber has very slightly different machining marks from the factory, which do leave their imprint on fired cases.

Here's problem number one - those machining marks do NOT stay constant. Firing the gun while dirty, using steel-cased ammunition, fumbling around while attempting to clear stuck shells; a great many things can alter the machining marks. Having the barrel throated and chamber polished -will- alter the marks as well. Everything from normal wear and tear to bungling to customizing can change the "fingerprint" of the gun, rather readily.

Problem number two is this - people who follow the law in purchasing a gun don't normally break it. As has been said, Maryland's law has resulted in absolutely ZERO solved cases. Crooks use either 1) unregistered/unfingerprinted guns, stolen or bought off the black market, or 2) stolen fingerprinted guns, which can only be traced to the original owner, not to the thief.