Low velocity on Custom Pro
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=173132
Printed Date: 30 January 2026 at 4:41am
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: Low velocity on Custom Pro
Posted By: k4dv
Subject: Low velocity on Custom Pro
Date Posted: 29 January 2008 at 10:14am
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I am having problems with low velocity on a Tippmann 98 Custom Pro E. It has an expansion chamber and regular hopper on it. It did have a cyclone, but I took it off and closed off the port on the side. Can't get velocity above 220 fps. Tried different tanks, same result. Do you think i need a stronger bolt spring? It does have ACT as well. Thanks for any help. |
Replies:
Posted By: SSOK
Date Posted: 29 January 2008 at 11:50am
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I dont see why your velocity would be so low. Try putting your old powertube in, and if that doesn't work install a new spring.
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Posted By: Mack
Date Posted: 29 January 2008 at 2:43pm
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Do you have any other after-market stuff on it? (Stocks, barrels, etc.)
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Posted By: The Guy
Date Posted: 29 January 2008 at 4:52pm
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You're turning the velocity screw OUT to bring up the speed right?
------------- http://www.anomationanodizing.com - My Site 
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Posted By: Ilford Rule
Date Posted: 29 January 2008 at 5:59pm
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Try a stiffer drive spring. This often helps. It hasn't helped me, but most other cases of this are a weak drive spring. Also, check that the detent isn't in backwards.
------------- CPro (w/ polished internals) 14" Bigshot BT SBS Various Rails NcSTAR D4B Macro AA 68/45 
CCI Phantom 45 Grips |
Posted By: k4dv
Date Posted: 30 January 2008 at 10:52pm
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I had the cyclone hopper on it, but removed it. Put an expansion chamber on it and the velocity won't come up above 230 fps. I am sure it is installed properly. I have put them on before. No leaks, plugged the port where cyclone gas line hooked up. Turned adjustment screw all the way out, no change. Thanks for any ideas. Will a drive spring from any 98 work or does it have to be one from an ACT bolt gun? ------------- Tippmann 98 Custom Pro E |
Posted By: Mack
Date Posted: 30 January 2008 at 11:52pm
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When you say the velocity screw is "all the way out" what exactly do you mean?
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Posted By: k4dv
Date Posted: 31 January 2008 at 9:04am
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The velocity screw is out to maximum, not removed. It doesn't seem to matter if it is in or out, not much change in velocity. I have a couple of Madman drive springs for a 98, i will give one of those a try and see if it fits. thanks ------------- Tippmann 98 Custom Pro E |
Posted By: Mack
Date Posted: 31 January 2008 at 11:08am
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It very well could be the drive spring as the I-man said, but there are other possibilities as well. The velocity screw on Tippmann markers works by interfering with the free flow of propellant from the valve to the chamber. This means that the approximately the same amount of gas is used for every shot and ball speed is controlled by how fast it is released. Essentially, the farther in you turn the screw, the more in the way it is and the slower the air is released. The nature of this adjuster means that there is a point (approximately four complete turns out from all the way in) where screwing it any farther will no longer increase velocity. In fact, depending upon other variables (like how tight the screw fits in the valve) turning it out farther can cause air loss and decreased velocity. I suggest turning the screw all the way in, then backing it out three complete turns and working from there with a chrono. I am still curious as to what type of barrel you are using. Longer barrels tend to require more air as do barrels with tighter bores. If you were using a long barrel with a tight bore, the combination of these factors could also cause the problem you describe. In that case your best solution would be an after-market spring or rear velocity adjuster. Backspin barrels tend to require additional air as well. Finally I have seen barrels that didn't fit well (on older "broken in" markers) work loose and lose pressure around the end of the barrel at the receiver. -------------
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Posted By: tallen702
Date Posted: 31 January 2008 at 8:58pm
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I'm just taking a shot in the dark here, but... did you use teflon tape when installing your vertical adapter and expansion chamber? ------------- <Removed overly wide sig. Tsk, you know better.> |