If it's a used rifle then the rubber set may help. If it's relatively new and shows no obvious signs of wear or cracking then you really don't need it.Thanks guys, so with HPA I should prob get the rubber set and a striker spring (the striker spring is that spring in the bolt right?) also I knew that I only needed that one piece, where does it go? Also in the bolt?
Also, yes the striker spring is what's in the bolt. Don't forget to unscrew the set screw in the rear before trying to unscrew the spring screw. Confused yet? Here's a picture to help. The striker spring is the spring shown. The plastic nub which holds it down is two pieces so don't freak out when it comes apart.