I did not do that test but I will admit, the 50 AT would be a serious test for any muzzle brake. I would suspect my PK and your brake would perform very similiarly in recoil reduction.
Yours has a bit more surface area, mine has the better gas redirection control, I would say it would be about a wash in the end. May have to test and see what happens.
Might need three sheets of plywood for the first, no brake test shot!!!