I had a 308 but they are junk . I hate to know I had to set in a tree with one . I take my 270 over it any day . Never shot the 50 cal but I know that would be the way to go , lol ....
I shot a friends Weatherby .270 and Remington .338 at 300yds side by side last summer. I actually did a better grouping with the .270, I think was the trigger on the Remington, it had a slighter harder pull, and just didn't feel as nice to me as the Weatherby. The biggest rifle I actually own is a Winchester model 94 30-30 circa 1920's I inherited from my Grandfather. It's only iron sights, but the range on it is so short that that doesn't matter anyway. I still love it though, it's fun little rifle, and just big enough to take down a deer. I play with my brother-in-laws .300 winmag, and 22-250 alot too, that 22-250 is great for popping groundhogs or jack rabbits at 100yds. Yes I kill small animals for fun, I'm a terrible person
. But to be fair I only do it because they make holes for me to twist my ankle, and get tractors stuck in.
From what I've read and seen the Barrett .416 is the new best uber-long rifle out there. It stays supersonic longer then a .50 BMG and carries more kinetic energy past 2200yds. Although it doesn't have the energy to punch through concrete and brick walls at shorter range like the .50, so I suppose the .50 BMG will remain king as far as military use.