This can vary widely according to the needs and requirement of the agency involved. However, overall, probably the most commonly used caliber handgun in use by civilian (and military) law enforcement is the 9 millimeter. VERY few law enforcement agencies utilize a revolver as their standard-issue sidearm any longer, and the semi-automatic pistols have taken over this role. While MANY arms manufacturers produce handguns in this caliber, the Glock is among the most common.
Los Angeles Police Officers have a large selection of sidearms. Anything from the Glock series to your standard Baretta. Judging from other sources, it is most likely the Glock 17 & 18, as well as the Baretta 92F are the most popular side arms.
Glock has (estimated) 60%-70% of the U.S. law enforcement market for sidearms. The most popular models are chambered in .40 caliber.
In the US, POSSIBLY a 9mm Glock pistol.
The official sidearm of the US Military is the Beretta M9, 9mm Parabellum pistol. I would imagine that at the level of operations the Navy SEALS are at, the individual can carry the sidearm of their choice. This may well be the M9, but another popular pistol is the M1911A1, .45ACP which was the official US Military sidearm from 1911 until the 1980's (before the M9). I don't know of any restriction regarding their choices. I doubt many would carry a .22LR Derringer though :)
One of the most popular exports in the US is machines and engines. Another of the most popular exports in the US is a variety of electronic equipment.
Califonia is the most popular state in the US
As of 2011, the most popular song in the US is probably Firework by Katy Perry.
The most popular spice in the us is the peper.
they are the most popular entertaniers in us,uk and everywhere
The most popular sports in the us are football baseball and basketball.
The Angus is the most popular for beef cows. The Holstein is the most popular for dairy cows.
One of the most popular roadsters in the US is the Mada Miata. The Porsche Boxster is aso another very popular roadster that is sold in the US.
The most popular type of Christmas tree in the US is the Pine tree.
The NFL and College Football are really popular sports watched in the USA. Football is the most popular spectator sport in the US.
It was the .45 ACP until about 20 years ago when it was phased out and replaced by the 9mm.