I own three rifles that have David Gentry's "quiet muzzlebrakes" on them.
DG is right. All of the holes in the brake are set at a 45-degree angle away from the shooter. The brake directs all of the muzzle blast down range away from the shooter. My wifes 300 win mag with a Gentry muzzlebrake on it kicks less than her 270-winchester. Her 7mm RUM with a Gentry brake & a Sims limsaver recoil pad kicks less than her 270 also.
You can reach Mr. David Gentry at (406) 388-GUNS.