There is a a .50 cal. upper which allows use of the standard ar-15 mags the ammo which is a lengthened 50 ae case feeds in single file,a 20 round mag holds 7 of the .50 cal beowlolf cartridges a standard 30round holds ten  www.alexanderarms.com  ,currently in use by spec op guys in the sandbox.  you get pretty much the same smackdown as a Barret 82 but in a much more portable package get yours now as regulation is pending to make 50 cal a class 3 item,the same way they took away the striker style shotguns,overnite they were classified as destructive devices.  $649.00 can't beat it, best of all its the ultimate Caifornia legal semi available.Those 400 grain bullets work wonders on all sorts of stuff, your only allowed ten rounds in Cali anyway so you may as well make them the best.