If you have the cash and you are set on getting an H&K, Id say go with the Mk23. Its a reliable gun, AND its a .45 ACP. If I were you Id go with something in .45. I have a .40, a .45, and a 9mm. The .45 has some serious power. I hit the round bottom part of a fire extinguisher that was laying on top of a bucket from 75 yards. The fire extinguisher went about 8 feet back, and the bucket it was on flipped over.

My .45ACP is a Springfield XD45 Tactical Model (5in barrel), and the .40 S&W is a Taurus PT100 also with a 5 in barrel.

Dont get me wrong, I love my .40. Its the gun I keep in my car for self defense (mainly because it costs less so I wont be AS mad if it were to get stolen).

A .45 is just fun to shoot.

Also, Id look as some 1911 variants. They come in different calibers, but the standard is .45. And they are legal in Cali because most only hold 7 or 8 rounds. Kimber, Para, Colt, & Springfield make some great ones.