When my brother and I both recently acquired pietta 1858 Remingtons ( mine is the sheriff), we went to the range and had issues with the cci #11 caps falling off the nipples of unfired cylinders when shooting, even when pinched. Others on the forums have mentioned this also. I started “crimping” one side of the caps with needle nose pliers, which flattens one side making them fit tighter which helped. You can do two at a time , doesn’t take long to do a whole tin. Anyway, I finally found some #10 Remingtons at a gun show, which my brother tried (I had already switched to slikshot) and he had no more issues. The stock pietta nipples on our guns do not play well with #11 cci caps. Many on the forum have had this problem.Just got one used. What is the #11 nipple issue? Iv been trying to find #10 for it but can't