How often should I replace internal orings, seats, etc.??

[MikeCouves]

Title...

[PyRo]

Well, as long as you take care if it the seals should last several years. As for reg seats, every time you take the valve halfs apart you should change it. Leave the halves together, untill you have eratic shootdown problems, then open it up and replace.

[BlackVCG]

Just use a high quality oil like KC Trouble Free, oil the gun before and after each day of play and your o-rings will last you forever. Don't take the valve apart unless you have to. The reg. seat should be replaced more often if you're using Co2, notice erratic velocity, or have excessive shootdown.