 Machine guns, as their own class of firearm, are not subject to requirements of other class firearms.Distinct from simple shoulder stock kits, full carbine conversion kits are not classified as short-barreled rifles.By replacing the pistol barrel with one at least in length and having an overall length of at least , a carbine converted pistol may be treated as a standard rifle under Title I of the Gun Control Act of 1968 (GCA).