Kanzutu has it right: after getting a proper stance, work on hitting the target. Best advice I've ever gotten about heavy recoil rifles is it doesn't recoil any less if you miss the target.
Colorado is right about the recoil of the 50BMG. However, try shooting on a line of people similarly equipped: the gun you are shooting isn't the problem, it is the muzzle brake blast from the guy next to you that clears the sinuses. If you ever find yourself shooting 50's in a group setting, pick a spot at the end of the line so you only get hit in the face by one rifle's blast not two.
Colorado is right about the recoil of the 50BMG. However, try shooting on a line of people similarly equipped: the gun you are shooting isn't the problem, it is the muzzle brake blast from the guy next to you that clears the sinuses. If you ever find yourself shooting 50's in a group setting, pick a spot at the end of the line so you only get hit in the face by one rifle's blast not two.