Google 77 gr service rifle load data. Highpower shooters cracked the code for 77 gr smk ar loads quite a while back and there is a ton of info available from their experience with this bullet and varget/rl15/4895/aa2520/tac/benchmark/vv540/....
Back in the 80's/90's when 308 was still a viable nra/cmp service rifle option the joking answer to new shooter inquiries on load suggestions was usually something like: 168 gr. Smk, lc brass and 42.5 grains of "something black" meaning any appropriate m14/m1 grand speed powder. Nowadays the internet and liability makes it harder to be so flippant with strangers but if you look at enough threads using the Google query I suggested you will see similar-ish patterns emerge for each of the powders listed above for reliable/accurate mag length ammo that should shoot at least 10 ring accuracy at 600 yds sling supported, developed by shooting a lot of rounds through a lot of different guns by a lot of different people and the answers being fairly consistent.