Each rifle is quite different. 1:10 would be an unusual twist. 1:9 is common.
You can buy Sierra 69 MatchKing bullets, or Hornady 68gr.
4895 or Varget are good powders. Load 23 to 26 gr in 0.5 gr increments. 5 of each. Shoot for groups. let barrel cool between groups. You will find one of them shoots best.
Be prepared to bring some ammo home, to pull the bullets. Your rifle might show pressure before you get to 26 gr.