Hello,

I have a Tippman custom 98 that is shooting at an extremely high velocity. I'm talkin between 365-391 FPS. My 98c has a cyclone feeder installed and I regularly use a flatline barrel with collapsable stock. I also have a 14" .68 caliber lapco barrel. I use Co2 with my gun, not HPA 

I went to a tournament last weekend where my gun chronoed at 375 fps with the velocity adjustment screw flush with the outer casing. Seeing as this was much too high I adjusted the screw inward as far as it could go and got it to go only to about 360 fps. I had to use another gun.

I came home and took my gun all apart, cleaned it inside and out and tried again, only to have the same problem. I tried it with the lapco barrel installed and it shot at 390 FPS!!

I've been reading through these maintenance forums and only suggestion that I could see that remotely fit my situation was that perhaps the hammer spring was very strong, but shooting at 370 FPS with a flatline installed seems to be a bit much for just a strong spring.

Also, it used to shoot within acceptable levels before this.

The only other thing I could see is that perhaps when I installed the new powertube for the cyclone feeder I did something wrong? I don't know.. any suggestion would be greatly appareciated, I have  nice gun... I just wouldn't want to play with it and hurt someone cause it's up WAY too high.

DeeV0n wrote: Hello, I have a Tippman custom 98 that is shooting at an extremely high velocity. I'm talkin between 365-391 FPS. My 98c has a cyclone feeder installed and I regularly use a flatline barrel with collapsable stock. I also have a 14" .68 caliber lapco barrel. I use Co2 with my gun, not HPA  I went to a tournament last weekend where my gun chronoed at 375 fps with the velocity adjustment screw flush with the outer casing. Seeing as this was much too high I adjusted the screw inward as far as it could go and got it to go only to about 360 fps. I had to use another gun. I came home and took my gun all apart, cleaned it inside and out and tried again, only to have the same problem. I tried it with the lapco barrel installed and it shot at 390 FPS!! I've been reading through these maintenance forums and only suggestion that I could see that remotely fit my situation was that perhaps the hammer spring was very strong, but shooting at 370 FPS with a flatline installed seems to be a bit much for just a strong spring. Also, it used to shoot within acceptable levels before this. The only other thing I could see is that perhaps when I installed the new powertube for the cyclone feeder I did something wrong? I don't know.. any suggestion would be greatly appareciated, I have  nice gun... I just wouldn't want to play with it and hurt someone cause it's up WAY too high.

what was the temperature outside? on hot days, your gun will often times shoot much higher than it normally would. I only mention this because you said your gun has shot within acceptable limits before.

the main spring's spring rate (the spring that's inserted into the rear bolt) is what dictates how hard the bolt hits the valve, how much air is released, and therefore how high the velocity is. i'd suggest one of two things: cutting one coil off the spring at a time, chrono-ing after each cut, or buying a spring kit, and switching out your spring for a lighter one. modifying/switching out the spring will do two things: first off, it'll lower your velocity to sufficient levels. secondly, it'll allow you to back the velocity screw so that it's flush with the inside of the powertube, therefore getting optimum efficiency out of your marker.

It wasn't very hot, warm enough so that you could wear a sweater or a t-shirt. It seemed to be about optimal conditions for play that day actually.

I will most likely try modding the spring then, if that doesn't work I can always buy a new spring kit later.

Thanks a lot for the advice.

Ok, I am guessing that he put the replacement powertube in that comes with the Cyclone feeder. I skimmed, saw the word powertube and thought he might have put in an aftermarket one. If you used the powertube from the cyclone kit, you shouldn't have issues as it is still GTA. How about the stock? Compare the depths of the holes that the spring fits into to insure they are the same depth. If the hole is more shallow, it can increase the pressure on the spring and cause higher FPS.  What type of stock is it?