Blah.I started with 556. Then I went to 300BLK, now I am at 762.
762 just gives you more. More thump, more range, more forgiveness for less than great placement.
I am not sure how it works for others, but for me I rarely see a single hog. I see sounders full of them. Anywhere from 4-5 to 20+. So I get one good shot, and after that it is a free for all. They are running everywhere and you are shooting COM.
My advice is do not buy anything else till you get here. A lot of what you have is not optimum or is costly and locks you in (like SF muzzle device).
Right now the best deal is an DPMS LR-308 lower kit from CDNN.
DPMS LR308 COMPLETE LOWER WITH STOCK GRAPHITE BLK (cdnnsports.com)
Then get complete upper from the usual places and are in business.
DPMS... (D)idn't
(P)ass
(M)ilitary
(S)pec
Mostly just busting chops. They make decent guns for the money.
I've discovered I'm a bit of a snob anymore and probably would build off an AERO set or some such. Maybe look around for something a bit nicer even.