Messed up accuracy - Precision Armament M11 Severe-Duty Muzzle Brake

Purchased March 8, 2019 and put in on a 20" 6.5 grendel and the gun never shot right, 6.5 creedmoor same problem, today on a 6 mm creedmoor and accuracy went to s*it. Today I also shot the 6.5 grendel without any brake and shot 5 shots a 3/4" at 100 yard. Really disappointed in the Muzzle Brake. It does keep the muzzle down but 3 to 5 inches in a 1/2" moa gun with many different bullets and loads and a years work lead me to the conclusion that this brake is not really that good. Only if you want to shoot a a 6 inch target at a 100 yard then it would be OK.