Building a DPMS 308LR and am undecided what cal. to make it. Ive already had a 24" bull in a 308 and was thinking about a 260 with a 20" or 24" barrel. This is nothing but a F@ck off rifle to shoot 1000yards and shooting PDogs, and will be wearing a 5.5-22x50 Nightforce. Any suggestions, Ive...