Federal law in the United States dictates a minimum barrel length of 16 inches for rifles and 18 inches for shotguns. Anything shorter is classified as a short-barreled rifle (SBR) or short-barreled shotgun (SBS) and requires registration with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) along with payment of a tax. A firearm with a barrel less than 16 inches or overall length under 26 inches is considered an “Any Other Weapon” (AOW) and subject to different regulations. State laws can further restrict these parameters, often mirroring or exceeding federal mandates. A pistol with a brace, regardless of barrel length, is generally not subject to these restrictions unless it meets the criteria for classification as a rifle.
Maintaining adherence to these regulations is crucial for lawful firearm ownership and operation. Understanding the legal minimums prevents unintentional violations, which carry significant legal consequences. This legal framework helps control the proliferation of easily concealable firearms while respecting the Second Amendment. The National Firearms Act of 1934 first established these parameters, largely in response to the widespread use of sawed-off shotguns during the Prohibition era. These restrictions have been refined and clarified over time through subsequent legislation and court rulings.