The U.S. Army has ordered another 100,000 M9 9mm pistols, each costing $640. The U.S. military (mostly the army) already has over 600,000 M9s. The U.S. military adopted the 9mm pistol in 1985, largely to standardize ammunition with NATO and to replace the M911 .45 caliber (11.4mm) pistol with something smaller and lighter. All other NATO states used 9mm for pistols. The U.S. also noted that most 9mm pistols were carried by officers and support personnel, who rarely used them, in combat or otherwise. SOCOM (Special Operations Command) came into being a few years later and immediately began planning to bring back .45 pistols for its commandos. Actually, many Special Forces and SEAL operators never gave up using the .45, as it was the ideal pistol for many commando operations.
The M9 is a 914 g (2.1 pound empty), 217mm (8.5 inch) long weapon that has a 125mm (4.9 inch) barrel and a magazine that holds 15 rounds. It replaced the M1911 .45 (11.4mm) caliber ACP. This is a 1.1 kg (2.44 pound empty), 210mm (8.25 inch) long weapon with a 127mm (5 inch) barrel and a 7 round magazine. Both pistols were only accurate at up to about 50 meters. The M1911 had more hitting power, while the M9 was a bit more accurate. Loaded, each pistol weighs about 230 g (half a pound) more.
Meanwhile SOCOM (Special Operations Command) has been allowed to adopt a number of .45 caliber pistols for its personnel. The U.S. Marine Corps recently ordered 12,000 .45 caliber pistols (for $1,900 each), mainly for use by its SOCOM (Special Operations Command) and recon troops. These MARSOC (Marine Special Operations Command) troops have, like the army, navy, and air force components of SOCOM, quietly replaced most of their 9mm pistols with .45s. For the last few years the marines have been supplying their special operations troops with older M1911 model .45s, refurbished (or built from scrounged up parts) in a marine-run facility.
There are several improved .45s available because of demand from police departments and government agencies (like the FBI). In the 1990s, SOCOM adopted the Heckler and Koch Mk 23 SOCOM model. This is a 1.47 kg (3.2 pound) .45 pistol with a 12-round magazine and the ability to carry a silencer. It is expensive, at $2,400 each. Loaded with a silencer and laser aiming device the Mk23 weighs 2.29 kg (5 pounds). The Mk23 is a precision weapon, capable of accurate fire at 50 meters (51mm/two inch shot groups). The Mk 23 is for offensive operations while the lighter and cheaper USP Tactical model was later introduced for personal protection and other duties not requiring the heavier Mk 23.
Over the last decade American troops in Iraq and Afghanistan discovered, through combat experience, what types of weapons worked best at close range to take down the enemy. It was the same with SWAT teams and commandos all over the world. When conducting a raid and finding yourself up close and personal with someone trying to kill you, there is a need for a heavy caliber pistol or a shotgun (firing 00 shot or slugs). The premier pistol for ensuring you take down someone is still the .45 caliber (11.4mm) or .40 caliber (10mm, but only with a heavy bullet) pistols. These weapons are light and handy, compared to assault rifles or shotguns, and have a long history of quickly taking down an armed and determined foe.
As the U.S. Army Special Forces discovered, if you are well trained and know what you are doing you should carry a pistol, in addition to your rifle. Not the official issue M9 9mm pistol but something with a bit more stopping power. The Special Forces prefer new model .45 caliber pistols, although 10mm weapons are also popular. The reason for this is that you are most likely to be using the pistol indoors, where your target is going to be really close. You want to knock him down quickly, before he can get at you with a knife or even his hands. Many troops are getting their own pistols and most commanders have been lenient on this issue. The same applies to shotguns. Although the army and marines have bought a lot of them (the Benelli M4 Combat Shotgun is a particular favorite), there never seem to be enough of them for some units (that spend a lot of time raiding buildings in hostile neighborhoods).