I would think so that it would break your hand or fly out of it. If you tried to hold on to tight you'd probally smack yourself in the head with it. My S&W .44 mag weighs 53 ounces. The only reason i an think of for some one making a gun like this is becuase they could.
It would break your hand. The stoutest pistol I ever shot was an EAA Thor in 45-70. To be honest really....anything above 44mag on a human is just overkill. I have seen snubbie 44mags and 50 AE Desert Eagles sprain wrists pretty badly. Id be afraid the gun would blow up on firing.
Considering the recoil on an M2 mounted on a tripod, I think that a .50BMG pistol would break every bone in your wrist before the gun went flying out of your hands. There's no way in hell that a human hand/arm can take that kind of force.