PMI Piranha user questions

[Dusty Bottoms]

Hey, I picked up some PMI Piranhas to fix up and play around with recently, a couple nice Piranha G3's and a older G2. I've never owned a Piranha before, had a Spyder Compact back in college, and some Illustrator F4's. I wanted to ask some more experienced Piranha users on here some questions.

I want to run these off of my Ninja SHP tank I have set to 900psi. I know these have a hammer spring and a valve spring and that you can use different strength springs to change velocity or performance. I just don't know how the two springs effect each other, if at all? If I use a heavier hammer spring to increase velocity, do I then have to use a different valve spring?

As far as valves go, would there be much benefit to using a higher flow valve when it comes to using compressed air? I bought a Magnaport valve just to play around with because they're cheap, just wasn't sure if it was needed.

Do Piranhas use standard Spyder cup seals? If so, what exactly wears out with cup seals, aren't they a plastic of some kind?

Any other peculiarities of the Piranha platform I should know about?

[Toestr]

Piranhas have an RVA so actual velocity adjustment would be done with that. Swapping out the drive spring would be done if the velocity is in the complete wrong range and needs a major increase/decrease. Swapping the valve spring is really only for if doing a low pressure build.

The stock valve and spring combo should be fine with HPA at ~800+ PSI. The Magnaport might give you a bit better efficiency with all else stock but would require some tuning. It would probably be good if you wanted to try doing a low pressure build.

Not sure on cupseal compatibility but the sealing surface that is pushed against the valve will eventually wear with cycling, debris and just being under pressure (this is really only an issue for rentals, you will get plenty of life out of it). Depending on material/age/care they can also dry out and crack with age (keeping them lightly oiled will prolong their life). This isn't a huge concern honestly. I don't think I've ever had to replace a cupseal on anything other than some well used ex rental Prolites. I have a rusted out ex rental 007 with the original seals that still seal perfectly.

My biggest recommendation for older blowbacks that only have one rubber nubbin detent is to make sure you get the longer nubbins (I believe Spyder had red ones and Techt makes Blue ones) instead of the short (usually black) ones made for dual detent guns or it will be rollout and double+ feed city.

[Dusty Bottoms]

Great info, Toestr, especially about the cup seals and detents. You reminded me that they did make different size detents for Spyders and clones.