I had a very difficult time finding a good load for my No1 Mk lll. After trying many 150 grain loads with at best 2" groups, I finally tried the Hornady 7.62 SP in 123 grains. This bullet yielded very nice .75", 3 shot groups after I improved the head space with a longer bolt head. I need to go back and try heavier bullets again but, the hunting season got in the way of my load development work.