Sounds like some are trying to make this too complicated. As someone stated earlier, use lead core .358” bullets and you will have absolutely zero problems. Consider the two specs of 8x57. I won’t go into great detail, as most have read the history. The early bullet diameter was .318” and the later bullet diameter is .323”. Countless .323” bullets have been sent down .318” barrels with mostly safe results. Oberndorf Mauser, and perhaps others, produced an intermediate 8mm barrel spec of .321” for some commercial sporting rifles that allowed the easy use of both .318” and .323” ammo. I had an 8x60 Oberndorf barrel like this. So, go get some .358 lead core bullets and have fun.