I just got a .50 Beowulf upper for my AR-15 and cannot wait to take it out. Large bore would be a good deterent. Shoot a few and watch the other run in shear panic as they leave their friends half and half bodies lying on the ground.
I looked at the .50 Beowulf, and it would certainly have its applications (besides murderous mobs, even). Have a look at the Stag 6.8 SPC II with 1:11 twist, if you haven’t done so already (especially terminal ballistics). [Ballistics nerd here. Not much danger of murderous mobs here, in the middle of frozen, high-altitude nowhere.]