I'm impressed with the 6.8 after only a month with one. This rig weighs 7.5 as it sits, only cost $911(including scope and mounts), and shoots moa frequently. I just built it the first part of January, so only got in two late season doe with it. After busting shoulders on both and still getting exits with the 120SST at 2590 MV, I feel fairly confident it's going to be a winner for medium game. With a .400 BC, it's not too bad and offers more than the 5.56 in my eyes. It's so much easier to tote vs an AR10.
You can get 90 grain bonded Gold Dots for only $9.99/box, so ammo isn't too bad. Many claim the GD loads shoot quite well and perform great on pigs.
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This is what ive come to know.IMHO I went 6.8 spc for deer,pigs and HD as well instead of .556 . Or like others have said I grab the bolt...22-250 , 243 , 30-06 if needed.