Velocity irregularity

[Snakechit]

I have a new RTpro with X-valve, lvl-X, and ULT. At the chrono. I get a shot to shot range of about 40fps! Ranging from 266 up to 305 (These were back to back shots!) The normal range is not always this drastic, but still has a range from ~270 to ~290fps and rarly less then +/-8 fps . These shot are without holding the trigger before the 2nd shot and with about a 1 second rate of fire. When I hold the trigger, the way a Mag is suppose to be chronographed, the results are just as erratic.

In an attempt to diagnose the problem I have used 4 different air systems:
*2 Centerflag Dynaflow tanks with a regulated output of 850psi
*Nitroduck Megareg with a regulated output of 800psi
*PMI screw-in with a fixed output of I believe 800psi
I have also tried 2 different barrel systems:
*Stiffi Switch Kit with a .691, .689, and .687 back (.685 not used due to paint size)
*Dye Boom Stick with a .689 back
I have also tried many different paints: Draxxus Blaze, PMI premium, and many others.
None of this has fixed the problem!

The most frustrating part is that when I first received the marker and after I sent it back to the factory I received a printout from their chrono with 3 shot speeds. All of which are +/-2 fps. I have never seen results like this over the chrono.

Please help, at this point I am willing to try most anything short of throwing the gun out the window. :confused:

P.S.: What is the normal range of fps on a mag?

[calcan311]

You are lubeing the power tube right. Try a larger carrier and or remove some shims from the level x. I have found If you have to much fricrion on the bolt your velocity fluctuates more.

[Snakechit]

I have tuned the lvl-X to have the largest carrier without leaks. And I have 3 shims installed, the least I need to keep the bolt from not resetting.

[calcan311]

Remove all the shims and chrono again. The shims add a little friction to the bolt. If you still have major velocity problems you may have a worn out reg o-ring. Good luck.

[cpt]

I am on my 7th mag and have fought this for 3 years. My main RT will go to some field and go -+ 5 fps and the next week the same chrono and same field have +-70 fps. Happened with my classic, X-valve, ULT ULE, with or without lvlX. I was wondering if my reg on my tank was flucating but used my son's and the same thing. I give up and just get it close, it doesn't seem to affect accuracy. I know how to chrono these. I was at a speedball last week and hand chrono 303, 245, 202. When I play they are all on target. Could be the temp, cheap paint, the sun and the moon not in alignment, ??? I always get chronoed and the gun works perfect but I have the problem and just live with it. I sent mine in also and replaced the reg seat and bla bla bla.