Ok here is an issue that I've never had before. Got a custom pro ACT and with etrigger. Running on HPA. When I cronoed at the last event the FPS was everywhere. At first it would be around 150 then as I adjusted it would go to 260/270 pretty much where I need to be. But here is the crazy thing. First shot 302 then 280 then 150 then 305 four times then 180 then 250 then 320. Eventually as I kept adjusting the velocity in and then out
(yes I did clearing shots between cronos) it calmed down to 260 give or take 15. What would cause it to go from 150 to 309 and everything in between? I've never experienced this before with a 98 and I own 3 of them.

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"Good... Bad... I'm the guy with the gun."

you have to add spring pressure. I just started to transfer my gun to HPA and my local tech said to add a new spring (longer for more tension) or add a small one to the end with the metal piece at the back. It gives it more consistancy for the air to regulate

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Only reason to get velocity fluctuations that big is partial rollouts. Check your ball latch. Most likely it is not stopping paint from rolling down the barrel. One thing is certain though; ading spring tension will not make a gun more consistant.

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Model98.org, Where Tippmanns Have No Limits

GONE TIL NOV 2013

The stock spring is fine for HPA. I still have a stock spring in mine from.... 2005?

I aggree with Magmoormaster. I think it is either your ball latch, or a terrible paint to barrel match.