This is a semi-auto or self-loading pistol chambered in the same round as the standard revolver. It is usually pretty big and weighs 3 pounds. It is a superior semi-automatic pistol compared to other similar pistols. It is also extremely reliable. It is extremely big for a pistol, though. It is meant to replace the revolver as the standard sidearm.
For size, look at an AMT Hardballer or the big M1911 the Terminator uses in the first movie. NKO members can also get the blueprints for it if wanted.
