What is the M249's system of operation?

What is the M249's system of operation?

• A. Gas blast, auto only
• B. Gas piston, semi-auto
• C. Short-stroke gas piston
• D. Blowback, full auto

Answer: (A)

The M249 operates as a gas-operated weapon that uses a piston driven by gas tapped from the barrel. When a round is fired, some of the gas pushes the piston, which then cycles the bolt to eject the spent cartridge, cock the action, and chamber the next round. It fires from an open bolt and offers selectable fire modes, including semi and full auto. This is not a blowback design, nor is it properly described as a “gas blast.” The mechanism relies on a gas-driven piston rather than a simple blowback, and it supports more than one fire mode.

The M249 operates as a gas-operated weapon that uses a piston driven by gas tapped from the barrel. When a round is fired, some of the gas pushes the piston, which then cycles the bolt to eject the spent cartridge, cock the action, and chamber the next round. It fires from an open bolt and offers selectable fire modes, including semi and full auto. This is not a blowback design, nor is it properly described as a “gas blast.” The mechanism relies on a gas-driven piston rather than a simple blowback, and it supports more than one fire mode.