Automatic firearm

The action of an automatic firearm is capable of harvesting the excess energy released from a previous discharge to feed a new ammunition round into the chamber, and then igniting the propellant and discharging the projectile (either bullet, shot, or slug) by delivering a hammer or striker impact on the primer.

In infantry support weapons, these rates of fire are often much lower and in some cases, vary with the design of the particular firearm.

Recoil plays a significant role in the time it takes to reacquire one's sight picture, ultimately reducing the effective rate of fire.

A prospective user must go through an application process administered by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), which requires a federal tax payment of $200 and a thorough criminal background check.

The tax payment buys a revenue stamp, which is the legal document allowing possession of an automatic firearm.

The use of a gun trust to register with the ATF has become an increasingly popular method of acquisition and ownership of automatic firearms.