The MK23 is a big. Big in the " nearly the same size as a carbine" range once you have the can and LAM on on.
The plain USP squares up just about level with a 226. The Tactical is a hair bigger than the 226.
For brands of a USP KWA/KSC is essentially the same for parts and function. The KSC ones in the past had nicer trades. KWA has ones with trades for 2011 but there still may be some Umarex marks on there too that don't belong.
Airsoft, where nothing is hurt but feelings.