Decent brake - Yankee Hill Machine Slant Muzzle Brake/comp 6.8/7.62/9mm 1/2x36 Threads

Used this on a 9mm AR build, fit perfectly onto the properly threaded barrel and managed to get it lined up straight with the provided crush washer. Much bigger than I anticipated it would look, but it does give the rifle a pretty aggressive look. It's not especially good at reducing recoil on this type of build, however, because there's relatively little gas coming out the barrel compared to a rifle cartridge, and also because of the direct blowback system. Would likely be much more effective on a 6.8 or 7.62 rifle.

All in all, a well made, nice looking muzzle attachment. Definitely not a necessary upgrade though - would not recommend purchasing solely for recoil reduction on a pistol caliber build!