SFT jumps from 220FPS to 300+, where to start

[mercpb]

Tech help please: Shocker SFT. Jumps from ~235 FPS and sputtering, to 300-325FPS with a very minor HPR adjustment. Feels unusual. HPR is fresh rebuild & bench tested, battery is new, no leaks/obvious issues.

I'm no good with these and I know the solenoids can go. Does this sound like solenoid or, suggest something else?

[Hobbes]

Was it working then suddenly stopped working? What is the bolt setup?

[Twisted G]

Does the sft have a piston reg seat? I had a luxe 2.0 long ago and when that seat went bad it did the same thing as your marker. Tiny adjustments of the hpr made the velocity swing crazy. no leaks either. Can't remember if it also sputtered.

[mercpb]

I'm testing with a fully rebuilt & bench tested hyper 2 --- reg is for sure good. Stock bolt guide, bolt looks like a NDZ stinger, delrin sleeve, NDZ ULP fire chamber. Cricket board.

Marker was put away ~12-14 years ago, I'm trying to get it back up and running

[RichM]

If the HPR is good and the battery is fresh/board is working properly then one other thing that could cause that would be bolt stick. If there is old grease/no grease in the bolt assembly it could be sticking until enough pressure forces it to move. If you've already lubricated the bolt assembly then I think the solenoid would be the next place to look, if its been sitting for 12ish years the solenoid valve might be failing.

[powpowpaintball]

Echoing what RichM said, I'd also replace all the bolt kit orings, if you haven't already. Zdspb.com should have the correct sizes