Ever wonder what makes a machine gun a ‘machine gun’, a short barreled gun a ‘SBR’ or ‘SBS’? What the heck is an ‘AOW’ anyway? The National Firearms Act (NFA) was created back in 1934, and like many laws the implications of the wording don’t always make the most sense. Read on for some simplified explanations.

•  any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The term shall also include the frame or receiver of any such weapon, any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun, and any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person.

Short Barreled Firearms (SBR/SBS)
The ticket to short-barreled firearms is the barrel length AND/OR the overall length (OAL). If the firearm is under the legal limit on either, the weapon is a NFA Title II firearm. OAL is measured with the stock fulled extended and muzzle device on AKA “as long as the gun will get”.

• A rifle having one or more barrels less than 16 inches in length, and any weapon made from a rifle, whether by alteration, modification, or otherwise, if such weapon, as modified, has an overall length of less than 26 inches.

• A shotgun having one or more barrels less than 18 inches in length, and any weapon made from a shotgun, whether by alteration, modification, or otherwise, if such weapon as modified has an overall length of less than 26 inches.

Silencers / Suppressors
The popularity of silencers or ‘suppressors’ has grown tremendously in the past few years. Simply put if a device quiets, muffles, distorts, or otherwise “makes a gun quieter”, it is a silencer and thus a registered NFA firearm.

• any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for use in assembling or fabricating a firearm silencer or firearm muffler, and any part intended only for use in such assembly or fabrication.

Any Other Weapons (AOWS)
AOW’s like their name encompass most everything else that isn’t one of the other NFA definitions. Many AOW’s are obscure like pen & cane guns, however some of the most popular options these days are ‘super shorty shotguns’ which are short barreled shotguns with a pistol grip that have never had a buttstock put on them.

• Any weapon or device capable of being concealed on the person from which a shot can be discharged through the energy of an explosive, a pistol or revolver having a barrel with a smooth bore designed or redesigned to fire a fixed shotgun shell, weapons with combination shotgun and rifle barrels 12 inches or more, less than 18 inches in length, from which only a single discharge can be made from either barrel without manual reloading, and shall include any such weapon which may be readily restored to fire. Such term shall not include a pistol or a revolver having a rifled bore, or rifled bores, or weapons designed, made, or intended to be fired from the shoulder and not capable of firing fixed ammunition.

If you are interested in more in-depth information there are some great definitions and information available on the Cornell Law website relating to 26 USC § 5845 and 18 USC § 921.