I have a model 11 on order right now. With the 1:10 twist barrel, I have heard the 168 grain bullet is the optimal weight for that barrel. Try a bipod, it will help a lot as well.
Would you recommend staying with the 150 grain bullets for the 1:10 barrel then?168 is actually optimal in 11.25 twist but it shoots great in a 10 at .308 velocity. I have a model 11 that i rebarreled with a criterion varmint contour .308 barrel. 10 twist and radiused 4 groove rifling. with 175 SMKs is 1/4 MOA