InstaPundit points out how the gun control crowd makes contradictory arguments:
"Saturday Night Specials" (cheap handguns) = Bad, must be banned
"Military Style Handguns" (expensive handguns) = Bad, must be banned
"Assault Weapons" (inaccurate, short-range rifles) = Bad, must be banned
"Sniper Rifles" (accurate, long-range rifles) = Bad, must be banned

Update: Glenn asked the rhetorical question about tracing shell casings, "what are you going to do, put a barcode on them?" A few hours later, the NY Times published a story about a couple of inventors who got US Patent 6,462,302 for making gun barrels that put a bar code on the bullet as it is shot. The NY Times has a weekly column about patents that do not necessarily have any commercial value. It doesn't sound very practical to me.