Ruger American 308.

I have a bunch of experience hand loading 308, but not for your particular rifle. You need to work up your loads for your rifle and find out what it likes the best. Start low and work up in .5 grain increments. Then once you find a load that works well, i.e. gives you a good group, then refine that particular load up or down by .1 grains and see what gives you the best group.

Paul
 
Try 44g of 4064, and 155g Lapua scenars. I've been doing a few loads for a local kid. His COL is different than my SPS 308, I'll try to find what his COL is on that rifle..

I started with 42, but 44 has worked the best.....hope it will help you.