Last year I bought a Sauer with 2 barrels; 7x64 & 9.3mm x 62. The 9.3mm also came with a few boxes of reloads. I don't know anything about reloading and did wonder at the risk of using unknown ammo. I finally decided to try the barrel but have noticed these reloads are a fairly tight fit into the chamber and that the outside necks of the cases are blackened after firing and I have had one round jam in the breach. Recoil is noticeable ! but accuracy seems good. Are the blackened cases a sign of anything ?