If you're looking to replace your entire bolt carrier and nozzle set, you may consider the G&P Bolt Carrier and Negative Pressure Nozzle Complete Set.
This complete set includes a hardened Bolt Carrier and a Negative Pressure Loading Nozzle Set and pre-assembled and ready for use. Simply take your old bolt carrier out, and drop this new set right in, and you're good to go!
Unlike the stock Western Arms system, the amount of gas used per shot by the Negative Pressure Nozzle Set is instead regulated by an independent valve inside the nozzle without the need for contact between a floating valve's plunger and the BB. Thus creating a steady output of gas regardless on how solid the contact between the BB and the nozzle, thereby reducing the chances of Projectile Dysfunction!
So if you're looking for a steadier output, whilst reducing the chances of misfires and other similar issues, the Negative Pressure Loading Nozzle Set is your perfect choice, along with the hardened Bolt Carrier you can keep banging away all day, and all of the night!