I am making my own brakes and my early testing has shown that they reduce recoil by 58%-70% depending on the cartridge. I make a 3 port, 4 port, and 5 port brake, which to use is based on what cartridge you are shooting. .223-.308 win is the 3 port, .284 win-.300 WM is the 4 port, and any of the RUMs and Lapua based cartridges are for the 5 port. if you are interested contact me via PM