I would like to make a Glock 21 Carbine in a way that does not require and SBR stamp. I would use the Gen 2 FAB Defense frame but to make it non-sbr legal I would have to have a 16 barrel. My idea is to use a LWD 6.5 treaded barrel and then have a light weight custom shroud/extension to extend the barrel the 16 minimum requirement. It would be pinned and welded I think a shroud is the way to go so that you do not have to use custom ammo since still dealing with a pistol length barrel and I doubt anyone will make a 16 solid barrel I know some of you think this is a stupid idea but I have built stupider guns I just need some input on the operation of the gun. Does anyone know if the shroud will interfere with the operation of the gun? Does anyone actually make a 16" barrel? All constructive comments are welcome Wanna kill these ads? We can help!