Comp for 9mm minor loads?

[Thompsoncustom]

I've got some time on my hands and some money burning a hole in my pocket so I might make a Open style gun just for target shooting at home. I've never had any experience with any Open guns but I'm guessing that the compensators are mostly for major loads. Is there any that work great for minor?

Gun will not be used to compete in any way just something fun for me to do.