A lot of variables in the question, but a couple things to remember. Mosin barrels range in tolerances, I find surplus ammo is usually around 0.310in and some of my mosins like 0.312 projectiles more. Also remember most surplus ammo we see these days is from the 70s and was made for LMGs not rifles unless you find some sniper ammo (which often sells for too much for surplus ammo) don’t expect it to be great. I also find that my mosins spread out groups once the barrel is warm-hot and I find surplus ammo warms up barrels faster then reloads or commercial. So you may get a decent group from the first few shots but I noticed the groups spread out quicker with surplus especially on a hot day. Using the surplus as components you can improved accuracy a bit but it’s not worth the effort in my opinion.