Discussion Forums

Scott Struif

Recently I watched a video by a professional guide demonstrating how to install and “time” a muzzle brake. The brake’s ports were mostly on the sides, but the top also had 4 quarter inch holes in it. “Timing” it consisted of installing shim washers of differ thicknesses so the holes on top were pointing straight up. The gun was a 7mm RM with a standard hunting stock.

The guide said the ports in the top eliminated muzzle jump altogether, because the force of the gasses exiting the top prevented the muzzle from rising. At first I thought that was amazing, but after I thought about it, I wondered how the small amount of air sitting in the barrel ahead of the bullet before the powder is detonated, could be compressed enough to counteract muzzle jump that occurs before the bullet leaves the barrel.

Muzzle jump occurs because the butt of the stock is lower than the plane of the barrel. It begins as soon as the powder detonates, and continues until all the gas following bullet has left the muzzle. I can see how the super-compressed gasses behind the bullet could produce a downward force on the muzzle after the bullet has departed the muzzle. But that’s only going to help return the barrel to its position before detonation. It’s not going to keep the muzzle level before the bullet leaves the muzzle.

It’s true that muzzle brakes reduce recoil because some of the gasses behind the bullet are expelled laterally instead of directly opposite to the recoil force. But that happens after the bullet is on its way. Any muzzle jump counteracted by ports in the top of the brake would have no effect on inaccuracy caused by muzzle jump that occurs before the bullet leaves the barrel.