[Redcloak]

 I can easily imagine a device using a laser and tiny mirror that could engrave something into the inside of the breech end of the barrel.

As an optical engineer, I can't. ;^)

[Cyber Liberty]

Well, if someone were to ask me, so I could help invent something that infringes the 2A, neither could I. But if somebody else were to do this, I’d obliterate the mark even if it’s illegal.