Another new guy from oregon , so I'm planing to retire in the next two years and I'm building up my firearm stash . I have 3 new AR'S ( 1seekins , 2 mega's - 55.6 , 1- 6.8 upper 16" ) so I want another ARP in 18/20" . But I can't make up my mind on which cal. to get (paper punching / SHTF gun ) . THANKS FOR ANY INPUT .