I am contemplating... just starting to think about... a heavy bullet AR. I have kind of narrowed it down to the .50AE, .50Beuwolf or .458Socom. I doubt the .475Tremor is really an option.

Can anyone supply me me with ballistics comparisons and factory ammo costs for these three? I am not set up to reload yet so factory ammo is my only option for a while.

Also, just out of curiosity, if I get an upper in that caliber, does the recoil buffer spring or anything else have to be changed on a standard AR lower? Could I use an AR-10 lower too?