from my older sierra manual imr 4831 ,w-w-case 1/10 twist bbl 26 inch ,Winchester large rifle powder 57.6 is MAX sooooooo start at55.5 a go up 1/2 grain at a time i'd bet 56.6 will be Golden, do not change any components of this load, the bullet is your 175 gn Sierra Match King old style, sierras oal was 3.340. one of my 30/06 wheres a 27.25 inch Hart ss/1/10 twist ,5.5 contur bbl,she dotes on H4350 wit 155's up to 180's. don't sell imr 4831 short, its not the newest or greatest but it set many records in many calibers , good luck keep us posted !