PAMAS G1 pistol
American designation for the Beretta 92FS.
The old guard in American society do not believe that the 9mm round is powerful enough, and there is to this day a debate ongoing as to the precise requirements of a military pistol. The latest request for tender for a large (300,000+) pistol contract has just been announced, and it's in .45ACP.
Initial complaints that the pistol had a weak slide were found to be inaccurate. The cause of the malfunctions was that the Special Forces types, who of course are above all laws including those of physics, were using a stupidly high loading which was beyond the design parameters of the weapon.
The third problem that the M-9 has suffered from is that of the magazines. The non-Beretta magazines that the US initially purchased suffered from very weak springs, so with even a little amount of dirt in the magazine, rounds would not be pushed up. Thus it was not uncommon for servicemen to purchase their own magazines for personal use.
As it's a much smaller weapon than the rifle, customisation is usually limited to a flashlight or a lasergrip (Government issued), which found greater use as a pointing device than a simple aiming aid.
Americans usually have pistols strapped in thigh holsters, accepting the blocking of a cargo pocket in the leg in trade for easier accessibilty for the sidearm.