Greetings all, first post! I am interested in shortening my Browning A5, but am having a hard time nailing down precise definitions. What I currently have is a 20-something inch barrel and a shoulder stock. I plan to shorten the barrel to less than 18", but overall length will exceed 26" (the same way the Tac-14 is legal). Where it gets hazy is the stock: the weapon has and was sold with a full length shoulder stock. Can I legally put a pistol grip on this shotgun? Is there anything illegal about putting a pistol grip on a (Ed: previously) shouldered shotgun? I understand that it would then become a "firearm" (I am of legal purchasing age) but cannot find information on the legality of a "shotgun" becoming a "firearm". Most interested in cited sources. New Mexico resident (with pretty lax gun laws) so primarily interested in Federal law.