I've told this story here before but here goes...
A buddy of mine has a KDF on his .300 Win mag that he takes elk hunting. The day before opening day several years ago we were shooting our rifles to check our zeroes. I checked mine and as I was about 25-30 yards behind walking back toward the tent he fired his rifle. HOLY SPIT Batman, I felt like someone had slapped me on both ears. It hurt...a lot!
A couple years later he killed a cow but had to shoot her three times trying to keep her from going down a steep canyon. When he got back to camp, he said, "Man, I can't hear a thing!" The ringing continued for a couple of days.
If you have a chance find someone that has a brake on a rifle and have them fire it while you're several yards behind them and see what you think.
I think that the guy that came up with the idea of muzzle brakes on rifles was really trying to impress his friends with how loud his rifle was and incidentally realized that it cut the recoil.
