Staff Writer (Updated: 4/15/2016):
After testing, the US Army requested several more changes to the Italian product that included a lengthened magazine for a longer grip and a new trigger guard for an improved two-hand hold. A lanyard loop was added to the base of the grip handle. Internally, the barrel was chrome-lined for longevity while the exterior body received a special coating called Bruniton. Beretta responded and delivered the modified form as the "Model 92F". Satisfied with their handgun, the Model 92F was adopted into the inventory of the US Army as the "M9" in 1990 and remains the standard issue sidearm of the US military to this day (2013).
Externally, the M9 features the same lines of its Italian cousin with its rectangular slide mounting the safety lever, gripped section for slide management, the ejection port for spent shell casings and a front and rear-mounted iron sight. Internally, the weapon takes on a standard configuration with the barrel over the recoil spring. The hammer is set at the rear and protrudes slightly from the slide. The grip is well-formed and patterned for a sure hold. The trigger assembly is curved in the usual way while the trigger ring is oblong and suitable for a gloved hand.
The M9 is chambered for the widely-used German 9x19mm Parabellum pistol cartridge in which fifteen are housed (staggered column) in the straight detachable box magazine fitting into the base of the grip. The weapon relies on the short-recoil principle through a semi-automatic action when cycling and uses an initial cocking action to prep the weapon's first cartridge into the chamber. Overall weight is 952 grams unloaded with an overall length of 8.5 inches, the barrel measuring 5 inches long within. Muzzle velocity is listed at 1,250 feet per second with an effective range out to 50 meters (164 feet). The M9 can be outfitted with specialized optics, aimers and lights to suit the firer.
The M9 was in circulation by the time of the US invasion of Panama (1989-1990) to unseat Panamanian dictator Manuel Noriega. From there, the weapon was featured with US forces in the 1991 Persian Gulf War and, more recently, throughout the actions in both Afghanistan (2001-Present) and Iraq (2003-Present).
As of this writing (2013), the future of the M9 is in some doubt for the U.S. Army is considering replacing the line with another, more modern, breed of handgun.