Bruce Gray of Grayguns.com is known as an expert in SIG P320s. His trigger kits are the best around for the P320. What you may not know is that he has done some custom work on H&K P7s.

He welds on an extension to the slide and then mills it into a compensator. He blends the extension with the rest of the slide. I am not sure if it is the lighting but the photo above there seems to be a slight difference in bluing where the comp is and the rest of the slide.

He turned one into a race gun with a frame mounted optic.

You can see a lot more pictures of the racegun P7 on HKPro forums.