A long gun is a category of firearms with long barrels. In small arms, a long gun or longarm is generally designed to be held by both hands and braced against the shoulder, in contrast to a handgun, which can be fired being held with a single hand. In the context of cannons and mounted firearms, an artillery long gun would be contrasted with a field gun or howitzer.
The actual length of the barrels of a long gun is subject to various laws in many jurisdictions, mainly concerning minimum length, sometimes as measured in a specific position or configuration. The National Firearms Act in the United States sets a minimum length of for rifle barrels and for shotgun barrels. Canada sets a minimum of for either. In addition, Canada sets a minimum fireable length for long guns with detachable or folding stocks . In the United States, the minimum length for long guns with detachable or folding stocks is with the stock in the extended position.
Examples of various classes of small arms generally considered long arms include, but are not limited to shotguns, personal defense weapons, submachine guns, carbines, assault rifles, designated marksman rifles, sniper rifles, anti-material rifles, light machine guns, medium machine guns, and heavy machine guns.
Almost all long arms have front grips (forearms) and shoulder stocks, which provide the user the ability to hold the firearm more steadily than a handgun. In addition, the long barrel of a long gun usually provides a longer distance between the front and rear sights, providing the user with more precision when aiming. The presence of a stock makes the use of a telescopic sight or red dot sight easier than with a handgun.
The mass of a long gun is usually greater than that of a handgun, making the long gun more expensive to transport, and more difficult and tiring to carry. The increased moment of inertia makes the long gun slower and more difficult to traverse and elevate, and it is thus slower and more difficult to adjust the aim. However, this also results in greater stability in aiming.