Don't do the Mk 23 if you are trying to go for realism.
Have you every picked one up before? There is a reason it is called an "Offensive Handgun Weapon System". It is a monster.
It is also universally derided and disliked. Yet another Ordnance boondoggle.
If you are going to have a gun that size, might as well take a sub gun with a folding stock....
Go to Lightfighter.com. Join, and do some searches. DO NOT ASK THIS QUESTION
though. You should find some interesting information if you are good a searches and can read between the lines.
Hint, a certain company made a certain extended .40 magazine and it wasn't for the civilian/LEO market....