My first muzzle brake was on a 300 ultra mag. I didn't have a problem with the recoil, it was pretty high but bearable
I put the brake on and was impressed.
The brake made a lot of noise, I wear hearing protection anyway, but it made it so I could shoot all day
My second brake was on my new 3006 because I recently had neck surgery. The brake again made it so I could shoot all day without great pain
I recently had a 6.5 PRC built and had a brake put on it while they were building it.
Really not necessary with the recoil on the 6.5 , but felt it might help protect my neck. The 6.5 PRC with the brake shoots like a 22 mag. Fun to shoot...
I have no idea why or what causes it, but my son's 7mm ultra sighted in at 100 yards with a Guide series brake shoots
.5 moa, but if you unscrew the brake, the group is around 2 inches. We have tested this many times at different temperatures in the range here in the yard. Puzzling to me but he never shoots it without the brake anyway.
One other thing We have noticed hunting whitetails is if you shoot a deer that is in a group, they don't run because they don't know where the shot came from due to the way the brake works.
Sorry for being so long winded....