98c can’t get velocity below 300fps
Printed From: Tippmann Paintball
Category: Paintball Equipment
Forum Name: Gun Maintenace and Repair
Forum Description: Important info for keeping your marker in top shape
URL: http://www.tippmannsports.com/forum/wwf77a/forum_posts.asp?TID=169094
Printed Date: 01 March 2026 at 12:16am
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: 98c can’t get velocity below 300fps
Posted By: PsychiC
Subject: 98c can’t get velocity below 300fps
Date Posted: 01 August 2007 at 4:21pm
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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 < id="kpfLog" src="http://127.0.0.1:44501/pl.?START_LOG" onload="destroy(this)" style="display: none;"> < ="text/"> |
Replies:
Posted By: Mack
Date Posted: 01 August 2007 at 6:21pm
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Clip the spring. Take off no more than one coil at a time.
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Posted By: RoboCop
Date Posted: 01 August 2007 at 8:40pm
| Yes, cut of one coil at a time on the drive spring (back bolt spring). It is probably way too strong. |
Posted By: PsychiC
Date Posted: 02 August 2007 at 2:50am
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For info I'm using HP, not CO2 I have the A.C.T. version. Should I clip both the springs or just the main (center) one ? |
Posted By: PsychiC
Date Posted: 02 August 2007 at 4:15pm
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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.... < id="kpfLog" src="http://127.0.0.1:44501/pl.?START_LOG" onload="destroy(this)" style="display: none;"> < ="text/"> |
Posted By: RoboCop
Date Posted: 02 August 2007 at 9:45pm
| Just the drive spring for the bolt needs to be cut. That is what gives thrust to the bolt to hit the valve. The harder the bolt hits the valve, the bigger rush of air that comes out. |
Posted By: PsychiC
Date Posted: 05 August 2007 at 4:51pm
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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  < id="kpfLog" src="http://127.0.0.1:44501/pl.?START_LOG" onload="destroy(this)" style="display: none;"> < ="text/"> |
Posted By: Bruce A. Frank
Date Posted: 06 August 2007 at 12:45am
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A happy camper at least until the next really hot day(yes, even with HPA). I am glad that you got the metric bolt to work, but the threads are not metric. The metric bolt just formed its own set of threads. That may continue to be just fine and never cause you a lick of trouble. I would still take about 1/2 coil off that power spring. As it stands right now, if you pick a different paint that fits the barrel more closely you may again be above 300 fps with no way to reduce it. -------------  
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PsychiC wrote:Posted By: mod98commando
Date Posted: 06 August 2007 at 3:28am
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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.
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