i only use the thompson center brand musket nipple replacement part. i switched to musket caps about 4 years ago.i like the musket caps because its much more fire power and its bigger so its better on the fingers as far as not dropping them. i never had a problem till this year and it has been a gradual one. the gun is a new englander caplock that they dont make anymore but looks kinda alot like a firestorm to me. thompson center will get this gun next week. i will let ya- know what they find.