Try some milspec that is copper washed steel case. Accuracy often varies with different ammo. Aimsurplus might have some. It will be 147grain. It is corrosive so run three very wet windex patches thru barrel to remove corrosive salts. Then clean normally. Do this on the same day you shoot. Leaving the salt in your barrel for even a week could start to damage the bore. Really.

If you EVER find copper washed steel case ammo with yellow stripe on bullet, BUY all you can afford. This is heavy ball(182 grain) and it is superbly accurate in Mosin 91/30 PUs and the SVT.