Certain DOD and private contractors carry the Glock 17,19, and 21. The 17 and 19 have NSN #'s and can be procured by specialized units via offical means.
The Sig P226 is also common as are custom 1911's(Colt, Kimber, Springfield, Wilson, etc.) and BHP's(mostly guys over 35 on the last two). They are purchased with private and or group funds. If need be they can be obtained via offical sources.
As most people asserted the average solider is not issued anything other than the M9(Beretta 92FS)or limited numbers of M11's(Sig P228). If they aren't high speed low drag it's a POW(approved or not)
The Glock 17/19's have been approved and procured for certain Aircrew units(USN and USAF) as well as authorized by the NIS and Army CID for certain personnel on a case by case basis. The have also been purchased in limited #'s for embassy security teams(read USMC) as well as some USAF security details assigned to NASA facilities.
The Glock handgun only KB's when retards shoot reloads or cast ammo through them.