Very effective brake - Precision Armament M11 Severe-Duty Muzzle Brake

The design biases the first port to do the lion share of redirecting the expanding gas and therefore pushes extreme side blast and concussion to either sides. It greatly reduces recoil and great to be used when you are all by yourself but not so great to your neighbor shooting lanes at the range. If you shoot mainly on the bench at gun range there are other more "polite" brakes. I used it on my AR-10 and my rifle felt like a AR-15. Highly recommended.