Short Barreled Rifles (SBRs) - this category includes any firearm with a buttstock and either a rifled barrel under 16" long or an overall length under 26". The overall length is measured with any folding or collapsing stocks in the extended position. The category also includes firearms which came from the factory with a buttstock that was later removed by a third party.
Short Barreled Shotguns (SBSs) - this category is defined similarly to SBRs, but the length limit for the barrel is 18" instead of 16", and the barrel must be a Smoothbore. The minimum overall length limit remains 26".
Suppressors (aka Silencers) - this includes any portable device designed to muffle or disguise the report of a firearm.
Destructive Devices (DD)- there are two broad classes of destructive devices:
Devices such as Grenades, bombs, explosive Missiles, Poison Gas weapons, and similar items and any non-sporting firearm with a bore over 0.50", such as a 40mm Grenade Launcher often used in conjunction with rifles. (Many firearms with bores over 0.50", such as 12-gauge shotguns, are exempted from the law because they have been determined to have a legitimate sporting use.)
Any Other Weapons (AOWs) - this is a broad "catch-all" category used to regulate any number of firearms which the ATF deems deserving of registration and taxation. Examples include, among others:
- Smooth-bore pistols
- Pen guns and Cane guns
- Short-barreled firearms with both rifled and smooth bores, etc.
- Disguised firearms
- Firearms that can be fired from within a wallet holster or a briefcase
- A short-barreled shotgun which came from the factory with a pistol grip is categorized as an AOW rather than a SBS, because the Gun Control Act describes a shotgun as “…designed or redesigned to be fired from the shoulder…”
- Handguns with a forward vertical grip. It is therefore illegal to place an aftermarket foregrip on any pistol without first registering it as an AOW and paying the $200.00 "making tax" imposed by the Act.
