Comp-Tac makes the MTAC for the USP .45c: Comp-Tac : Products
The MTAC is, IMHO, a great holster. Very comfortable.
This is a discussion on IWB Holster for an H&K 45C within the Defensive Carry Holsters & Carry Options forums, part of the Defensive Carry Discussions category; I've been trying to track one down with little success. HELP??? TIA...
Let me know if this interests you. It is a Mitch Rosen WKM Slimline IWB for the H&K USPc. I ordered it for my USP 40c and when it finally arrived (~8-9 months later), I had decided not to CCW that particular gun. So it has only been worn for a few hours around the house and then packed away as an expensive experiment.
Here's the Mitch Rosen webpage listing this holster and others.
And here's links to pictures of my holster, both sides, and with and without the firearm (NOTE: The thread showing in the pictures is from a scrap of carpet I used to prop up the holster for the pictures). The pictures are big, so I'll just post the links here instead of the live picture.
Double whoops I guess!
ETA: Make that triple Whoops! Didn't catch that it was not the USP Compact and .45, not .40 that we were talking about.
I'm going to go wash my glasses now!
My main carry is currently an H&K USPc .45. I carry it in an MTAC.
HK USPc .45
I just purchased this gun HK 45C. I have not been able to find a holster for this one. They are both very similar guns... in fact, when I DROS'd it we field stripped them. The slides and magazines were interchangeable. The shape of the slides are a bit different. The USP is squared off whereas the 45C is more rounded. I'm sure it will fit in the holster I currently use for my USP but I am a bit concerned about retention.