They are called compensators on handguns.
Many years ago I heard of someone making their own compensator for a 38Super and at one stage did have it venting up too much, to the point when the muzzle actually dipped upon firing. Very weird.
I should add - compensators are intended to reduce muzzle "flip" whereas brakes are intended to do this and reduce recoil. Some guys I know with muzzle brakes use them so they can see the shot travelling through the scope and not recoil reduction - I mean, these are on 223s and 308s.
I just recalled, I had a compensator on my M14, but they called it a stabiliser. Worked extremely well.
Last edited by mauserand9mm; 04/01/15.
