As said above use only 7.62X54R light ball (147 grain) or you will damage the receiver. Also the caution to keep the barrel from heating up is a good idea otherwise your groups will open up. I have found Czechicon Silvertip to be the most accurate 7.62X54R in my PSL. Additionally try to but only ones marked Cugir PSL 54C. The ones put together by the outfit in Tennessee, usually marked FPK, can be problematic.