Austin, I recommend you buy several different brand/bullet weights and try them to see which your rifle likes best. Use the same process for each ammo type (shoot from a cold, fouled barrel, etc.) and shoot several three or five round groups, then take the average.
I have a Vanguard S2 in .308 and it likes Rem CoreLokt 180gr. It shot a 9/16" group with this ammo, but also shot sub MOA with 150 gr CoreLokt, Federal 150gr and GameKing 168gr.