This civilian version differs from the official "agency" model is the lack of "SOCOM" marking on the slide, a separate range of serial numbers, and a "US Property" barcode on the serial number plate. It was designed and built from the ground up with special features for the ultimate in silencing, and shooter-friendly accuracy and handling. My first 12-shot magazine tends to confirm this.
While the barrel is threaded for a wide variety of suppressors, the H&K wet-and-dry suppressor, designed specifically for the Mark 23, is a special favorite with Marine room-clearing teams. Besides using water to enhance thermal efficiency, it disables semi-auto fire, requiring the shooter to manually cycle the slide for the next shot. A vertical foregrip is added for better handling.
In actual use, Marines claim this setup works better than any other handgun, SMG, shotgun, or rifle they tried. The only noise when firing is the hammer hitting the firing pin, which is about as loud as an office stapler. The slide being cycled makes a modest "zip-zing" reciprocating sound. The bullet hitting the target is usually very loud, but by then the target has stopped caring.
The Mark 23 can fire almost any kind of ammo that can safely make it down the barrel, including high-power oddities like 45Magnum. I mixed in some red-hot Double Tap .45 (200fps faster than standard), with no noticeable change in admirable shooting qualities.
It's like one of those Mercedes super touring cars you see at an important car show (or commercial), something one-of-a-kind with 4000 horsepower, top speed of 280mph, zero-to-sixty in 2.1 seconds, and more electronics than a next-generation manned spacecraft.
The Mark23 is real steel-and-plastic, was made in "reasonable" quantities, and is zealously maintained and used by civilians and federal agencies alike.