Any distance from 0-500 yards, open areas, little dense packets of trees. Also a town here wnd there. Using it in a WROL situation, where there must be one 'go to' caliber for everything. Must be avaible in a semi auto format. Ideas? Thought about the 5.56 but I don't like it past 300 yards because of the loss of velocity. I'm thinking either a 5.45 or .308, but I am open to any ideas really.