There is still some confusion regarding flash suppressors and muzzle brakes and there use on the rifle range particularly under the roof . Following are actual definitions of both but to make one thing very clear! I really doubt anyone would take more than one shot under the roof with a true muzzle brake because the concussion would ring your bell seriously if it didn't make your ears bleed!
A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a device attached to the muzzle of a rifle that reduces its visible signature while firing by cooling or dispersing the burning gases that exit the muzzle, a phenomenon typical of carbine-length weapons. Its primary intent is to reduce the chances that the shooter will be blinded in low-light shooting conditions. Contrary to popular belief, it is only a minor secondary benefit if a flash suppressor reduces the intensity of the flash visible to the enemy.
A flash suppressor is different from a muzzle brake, although they are typically mounted in the same position and sometimes confused with each other. While the former is intended to reduce visible flash, a muzzle brake is designed to reduce painful recoil inherent to large cartridges and typically has no effect on visible flash.
A muzzle brake or recoil compensator is a device connected to the muzzle of a firearm or cannon that redirects propellant gases to counter recoil and unwanted rising of the barrel during rapid fire. The concept was introduced for artillery and was a common feature on many anti-tank guns, especially those in tanks, in order to reduce the area needed to take up the recoil stroke. They have been used in various forms for rifles and pistols to help control recoil and the rising of the barrel that normally occurs after firing. They are used on pistols for practical pistol competitions, and are usually called compensators in this context.[