The limiting factor on a .50 brake is not recoil. It's blast. There are brakes out there that basically eliminate all recoil, it's simple engineering. The problem is there have been incidents of shooters getting detached retinas due to the muzzle blast.Not buying it.
This would still be way too much recoil for that lower. Someone is gonna wear that bolt where their nose should be.
I think Imma let someone else take that one out for a spin.
There are also brakes that provide a happy medium that an AR lower could handle with no problem and doesn't screw up the shooter with blast. A .50 upper on a AR lower is not a new thing.