98c can’t get velocity below 300fps

Guys,

while others have problems of not getting their velocity high enough, I
have the problem I can't get it low enough.

I've replaced the stock powertube with a JCS blue tube because the plastic treading was totally wasted. I've set the velocity screw all the way in but it would barely drop below 300fps. If set half way it shoots over 350fps ! While playing with the screw all the way in the screw was shot out trough the barrel. I suppose it wasn't large enough to cover the diametre of the tube. Now I'm using the stock velocity screw which is slightly larger. But when I put this all the way in it is beyond the thread of the tube. I can keep turning clockwise freely. I'm affraid it will shoot out sooner or later making a dangerous projectile and even now my 98c will shoot around 300fps which is too much !

How do I lower the velocity to 280-285 which is what is used to be with the stock tube ?

Please help,
a desperate tippie owner

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Edited by PsychiC - 01 August 2007 at 4:21pm

Yes, cut of one coil at a time on the drive spring (back bolt spring). It is probably way too strong.

Guys,

I've replaced the velocity screw because it was too small and might shoot it out again. I've replaced it with a descent bolt which fits fine in the thread. M8x30 ....and it surely won't fall out =)

I'll check the fps upcoming sunday and if it's above 280 fps I'll cut the main spring. I was advised not to cut the A.C.T. spring while this might cause problems with the A.C.T. 
Any suggestions are welcome....
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I've tested the marker on a chrono today.
It was shooting around 280 with the bolt completly in, which means I am a happy camper

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Edited by PsychiC - 05 August 2007 at 4:51pm

I have to agree with Bruce. If you can't get it down to about 250-260 then you have no room to adjust for velocity spikes or other variables.