Leaks out of blow off valve when over 260fps???

[Airborne Infantry]

My blow off valve leaks when ever I turn my gun up to anything higher that 260 fps. I know that the leak in the blow off valve is due to too high of airpresure in the valve body but I would think that I should still be able to get a higher fps.

Im using a standard automag with after market bolt, power tube spacer kit, 3000psi nitrogen tank, and thumb velosity ajuster. My gun is about 4 years old.

Let me know what you guys think!

Thanks

[Load SM5]

You need to replace your reg piston, they run $15 from the AGD store....http://store.airgun.com/acb/showdetl.cfm?&DID=17&Product_ID=48&CATID=6