hi, allcamo
here is a load that gives me 3/4 inch groups at 100 meters in my tikka new generation m65 338 cal.
74 grains imr 4350
225 grs nosler partition
federal large rifle primers

i notice your are shooting a non premium bullet, i use to do that until i had blow up on animals as small as a mule deer. imo the 338 cal is one of the best all around calibre, but the foot pounds impact is to much for standard bullets