Figured I'd follow up on this.
After a bunch of testing (~150 rounds of 75gr Hornady + other bullets) I've settled on 23.5gr of Benchmark with the 75gr BTHP Hornady for 2,675 fps from my 16" barrel. Best accuracy seems to be with S&B SR primers, of all things, with CCI 400 following pretty closely.
As posted above, I could push that bullet another 150 fps faster, which would help a little at distance, but the accuracy wasn't there. Trying to push the 77gr Nosler or Sierra faster didn't pan out either, running into pressure signs and bad accuracy sooner with both.
At 2675, it's still a good 150 fps faster than my barrel will do with Varget, and accuracy is good both bare and suppressed, generally around 0.5 moa for 5 shots. It seems to shoot consistently too, with different holds on the gun, weather, and bore conditions, which is more important to me than tiny groups when conditions are perfect.
I've given up on the 69 TMK for now, even though it can fly flatter with less wind drift at distance with the velocity I'm getting; it's just too inconsistent in my barrel. Some days I saw really promising groups, but the next day the same load might go into 1.5-2".
