CCI #10 caps are indeed too small for stated Pietta nipple. Try #10 Remington or RWS 1075, if
available in your area. If not available, try #11 CCI. I shoot Pietta Remingtons with stock nipples and
have for years. Never have misfires and have never understood buying after market nipples.
One more thing, if the #11 CCIs do not go own snug, give them a slight pinch before placing on
nipple
Good luck, and good shooting.