Plastic Nubbins 4-Pack
Nubbins are a simple device that prevents double ball feeding when using most brands of paintballs. Nubbins are used with twist lock barrels and install easily in the machines track designed to hold them. A fresh barrel oring is a good idea to hold them in place.
Once installed and the barrel is inserted in the body the nubbin will act to prevent a paintball from rolling forward into the barrel. Nubbins typically have a fairly long life. Not unusual to see them last entire seasons or longer with plenty of use.