The basic code is part of
308 and is the definition of "concealed". -
"
For the purpose of this section, a weapon shall be deemed to be hidden from common observation when it is observable but is of such deceptive appearance as to disguise the weapon's true nature."
There is similar language in ATF regulations and in fact there is a part of ATF regs that refers to "Hoax" weapons. Generally the Hoax issue relates to fake bombs and the like, but the language talks about "with the intent of targeting emergency or LE personnel to disrupt normal operations." I am trying to reach my contact at ATF to explore this a little.
In any case it is by no means clear tome that it is legal to disguise a firearm and carry it in public. Certainly here in VIrginia there is an issue with this. I think in the case of Virginia part of the problem might be that our permits are for the carry of a handgun concealed. The permit does not cover other devices like knives.