I have always built my own breaks out of 1" aluminum rod they are 2 inches long
with a 1/2 inch hole through the sides exit hole is .010 larger than the bullet.
the side holes are next to the barrel muzzel and the length of the space the bullet travels to the end of the break is 1 inch this gives a longer time for all the pressure to go out the side holes before bullet exits.
My 300 win mag, 300 wsm
& 338 win mag are fun to shoot now but they sure wasn't befofe the brakes