12fv 223 in 1:9

Whats a good load for a 75/77grain SMK bullet or similar?

In a 1-9 twist you are not likely to get a "good" load with the 77g SMK. If you want to try I would use 24g of Varget and shoot it at 300 yards. If it makes it to 300 accurately your probably good to go. Personally I would go with the 70 Berger.

Plus one for the 60 to 70 gn bullets

75 gr Hornady BTHP 24.2 Varget, CCI BR4, Win brass, .020" jump. validated to 400 Yds out of 10 FCP-K 1/9 .223

Is Varget a ball powder?

Nope

75gr Hornady HPBT @ 2.29" OAL (0.010" jump)
24.0gr Varget
Nosler, Lapua, RP, LC brass (doesn't seem to matter)
CCI-400/450

2850fps +/- 20fps (depends on brass) from a 26" 1:9 12FV barrel, and sub-half MOA at 200yd with five shots (the furthest I've shot it for groups). The first 100yd 5-shot group I ever shot with the aforementioned load went 0.464" CTC.

The above load works well from 2.25" AR mag length to the lands (2.30" on my barrel), but the 0.010" jump has provided the best, most consistent accuracy.

Same barrel pushes 75gr A-Max @ 2950fps with 24.5gr Varget @ 2.46" OAL, and while it's not quite as accurate as the 75gr HPBT, has proven to be 0.7MOA or better at 200yd.

I personally have not had as good luck with 68gr HPBT as I did with the 75gr HPBT.

77 SMK's shoot fantastically in 2 different Savages, and one Remington. Don't listen to anyone who tells you they won't stabilize.

24.1gr RL-15
77gr SMK
7 1/2 primers
2745 fps

Holds amazing groups @ 1K

Whats your average 1k group?

Best ever was 9.5" Otherwise MOA