My SBR is 9"and I've tried a number of different lengths and designs. Truthfully, there's going to be a lot of flash and noise with pretty much ANY muzzle brake when firing 5.56 rounds from a short barrel. From my experience, the best you can reasonably hope for is to simply direct as much blast as possible in a direction of your choosing. For any real control/reduction you'll need to go to a suppressor and be prepared to spend big dollars, especially for a good one, and do the class III route again.
"... Americans... we want a safe home, to keep the money we make and shoot bad guys." -- Denny Crane
Last edited by rachilders; 07-26-2012 at 12:54 AM.