Sell the barrel and get a WOA or Compass Lake barrel lol.... j/k homie I'm a few beers deep.
For 77gr TMK's the following worked for me. PLEASE make sure you work up to all of these powder charges and do not start with what I'm listing. Every rifle is different, and each situation is different.
23.4gr TAC
24.5gr TAC (over max, work up to with caution)
23.5gr XBR 8208
24.5gr Varget (compressed load)
I ended up settling on XBR 8208 for multiple reasons: Case capacity, availability, speed (not as good as TAC), consistency, temperature insensitivity, and who doesn't love the colors black and gold together ya know?