If you like to keep spare parts on hand for maintenance or replacement, add the appropriate size Plunger to your kit. Plunger service life varies from 10,000 to 25,000 rounds, depending on your firing schedule. When you replace a worn-out barrel or bolt or when the working end of your Plunger has been worn away by half, then it's time for a new plunger. You can also select shorter or longer plungers to fine tune the range of adjustments used for your specific firearm. This provides a tremendous amount of flexibility thanks to the modular design of the RIFLESPEED(TM) line of Gas Controls. For example; you've completed the setup instructions found on riflespeed.com and deter Mfg: Riflespeed