For what it is worth, I started on this quest 2 years ago when I started hand loading for my .308.
The Federal GMM (maroon and gold box) with SMK 168 grain bullets was rated at a muzzle velocity of 2650 fps.
The older Federal GMM (buff and blue box) with SMK 168 grain bullets was rated at a muzzle velocity of 2600 fps.
I tried Reloader 15 and got better results using 43.0 grains of RL-15 at 2.805 OAL and 42.9 grains at 2.805 OAL.
I was happy but not satisfied so I tried H4895.
I got even better results using 41.8 grains of H4895 with multiple depths from 2.800 to 2.815.
I changed bullets to Nosler Custom Competition 168s and got even better results with 41.5 grains of H4895 at 2.830 OAL. I also tried Berger 168s and got good results with H4895 with 41.5 grains and 2.820 OAL.
Then, using SMKs and Nosler CCs I tried Vhita Vuori N140 and got even better results using 41.9 grains with SMKs at 2.805 OAL and with Nosler CCs at 2825 OAL.
After I got slightly better accuracy with my Reloader hand loads than with factory ammo, I have given up trying to replicate factory ammo and have concenterated on getting the absolute best accuracy using whatever powder makes my .308 Savage Law Enforcement model 10 FP shoot as well as it can.
So far, N140 and Nosler CC bullets outshoot anything else I have tried in my rifle.
The SMKs shoot great, Hornady Match 168s shoot about the same, but the Noslers shoot just a bit better.