It is semi automatic and comes in two different colors,
USP.45 Tactical Classic
USP.45 Tactical Black
As of July 27 2012 a limited edition USP.45 was realeased but only for a limited ammount of time.
Limited Edition: USP.45 Tactical CamoBoth versions of the USP are the same in stats, the only difference between both versions of the USP is the USP Black cost and holds more ammo then the USP Classic.
As of right now both versions of the USP.45 Tactical are only available for credits.
The USP.45 Tactical is the first handgun in Uberstrike to have two different colors available. As of the 4.4.1 update, this gun no longer exists.