Describe the M9 pistol.

• A. The M9 pistol is a 9-mm, single-action, magazine fed, recoil-operation handgun chambered for the 9-mm cartridge.
• B. The M9 pistol is a 9-mm, semiautomatic, magazine fed, recoil-operation, double-action weapon chambered for the 9-mm cartridge.
• C. The M9 pistol is a 9-mm, lever-action, magazine fed, gas-operated weapon.
• D. The M9 pistol is a 9-mm, break-action pistol with fixed magazine.

Answer: (B)

Understanding how a modern military pistol is described helps you quickly identify its key traits. The M9 is a 9mm pistol that fires semi-automatically, meaning each trigger pull launches one round and automatically chambers the next. It feeds from a detachable magazine, so ammunition is loaded through a removable mag rather than a fixed chamber.

Its operating system is recoil-operated, specifically short-recoil: after firing, the barrel and slide move backward together for a brief distance, unlock, and then the slide continues rearward to eject the spent case and cock the hammer, while the slide returns forward to chamber the next round. This combination of semi-automatic action with a detachable magazine and a recoil-operated mechanism fits the M9’s design.

For trigger behavior, the M9 is a double-action/single-action pistol: the first trigger pull cocks and releases the hammer, and subsequent shots are single-action because the hammer is already cocked by the cycling action. The description that best matches all these traits is the one that notes 9mm, semiautomatic, magazine-fed, recoil-operated, and double-action. The other descriptions describe lever-action, break-action, or gas-operated designs, which do not apply to the M9.