The only factory ammo I have tested for accuracy was MFS. It was poor.
My handloads are all 55 g FMJ. I use a cheap ball powder similar to BLC2 and start low and work up, looking for the best accuracy, preferably well short of max. I only shoot CQB, so velocity is not required, just reliable cycling. Different rifle have different gas requirements. My Norinco develops a lot more gas in the action than the Dan Def and NEA, so the Norc load is very mild. So mild it won't run the bolt in the other rifles.