I was with a group of friends who are shooting long range for fun at metal targets, anywhere from 500-1000 yards. In the group there are .270wsm,7mm rem. mag, and 2 .300 RUM's. They all seem to shoot very good at those distances. What are opinions as to best accuracy of those 3 calibers and are there other options I didn't mention that ammo is readily available for? Thanks guys this is my first post.