Also worth reposting this from elsewhere I wrote it up, edited lightly for current context:
Long, long ago in a rifle class, the instructor had a little experiment at the end of the night shooting time, and we each, in turn, fired our guns while the others watched, to see how various muzzle devices worked. It was even ban period, before AR15s ruled the earth so other calibers and guns, weird muzzle devices, and bare muzzles.
Discounting the commercial spec ammo fireballs (we did some ammo trading to get solid results) almost all worked
fine. The three prong early AR, and the later but very similar AR18 one, both worked as well as the A2 flash hider.
Same for similar designs in other guns like the G3 birdcage looking thing.
The worst most did, like some Smith brakes and the Daewoo DR200 (despite looking like a bird cage copy), had tiny, tiny cartoonish licks of flame out the ports. So small, we were all pretty sure they wouldn't give you away to downrange bad guys in real life unless very unlucky and fighting in caves, or something.
Older designs, like those on the M14, were pretty mediocre. Okay for not blinding the shooter, but not the rest of the fire team; notable visible flame from even standing next to them.
If you want to really optimize, lots of cool things out there that claim to be awesomer yet and are from reputable people:
- SF Warcomp (also a suppressor mount, so could add a blast can IF suppressor mounts are legal in your state)
- SF SOCOM flash hider, an open prong design, just a flash hider I think but look
- BE Meyers 249F, though it is insanely expensive as you might expect, a variant on the open prong but they are very good at their jobs so reportedly it works well
- Smith Vortex, 80s design but early open prong and the vortex bit means twisted prongs so supposedly even better, the gold standard from back then, and still good today
