The Fort-12 (named Fort-12mk2 in Shadow of Chernobyl and 'Fora-12' in Clear Sky and Call of Pripyat) is a semi-automatic pistol that was designed in the late 1990s by Ukrainian firearms designer RPC Fort. Currently, this gun is issued to the Ukrainian police and security forces. It is also sold on civilian market. The Fort-12 incorporates improvements over the Makarov PM. The weapon is primarily used by rookie Loners and Bandits along with experienced, experienced Duty members, and veteran and expert Military elements. It uses 9x18mm bullets.
Interesting fact about the weapon's texture used in S.T.A.L.K.E.R. game series. The letters Форт-12Р (Fort-12R) you can see mean that this isn't the Fort-12 combat weapon, it's a Fort-12R model which fires traumatic rubber bullets. (See Fort-12R page at RPC Fort site. The in-game image is slightly different (the game developers added extractor and some space for it).)
Shadow of Chernobyl
The Fort-12 is sold by Sidorovich at a low and affordable price after you get the flash drive from Nimble. Wolf will award you with a free Fort-12 along with some spare ammo and grenades if you single-handedly clear the vehicle yard of Bandits. The Fort-12 is slightly less reliable and has lower handling than the Makarov PM, but is considered significantly better in the areas of ammunition capacity and accuracy.
The Fort-12 is still performs better than the Makarov PM but has lower handling. It can be bought from a variety of traders and uses the same upgrades used by most 9x18 caliber weapons. A free slightly upgraded Fort-12 is available to the player after accepting the job to kill the Military rescue squad attempting to rescue Major Khaletskiy. The Fort-12 is primarily used by experienced Loners, Bandits, some Duty members, and of course, the Military. You can also find a few experienced Loners who has this pistol with a few modifications.
Call of Pripyat
This pistol has become rare, since stalkers at the center of the Zone need better weaponry. It is sometimes possessed by rookie Loners and Bandits. However, superior .45 caliber pistols can be found at the start of the game.