X-Valve/Boomstick Inconsistency???

[abartjc]

I am having major problems with my Minimag. Here are the specs:
X-Valve with Level 10
14" Dye Boomstick
PMI 88/3000 Tank, preset at 850PSI

Everything else is stock. I am shooting PMI Premiums and also some Zap Spanks. Every place that I have read has recommended the Premiums for the Boomstick. What is weird is that when I take the barrel off, I can drop a premium right through the barrel.

My problem is:
When shooting over a chronograph, my FPS fluctuates like crazy! I shoot from 285 to 354 to 233 to everywhere in between. I have lubed EVERYTHING that can be lubed and that is not the problem. I did however change back to the stock barrel and shot a consistent +/- 8 FPS.

Should I send the barrel back? Should I try a different type of paint? What are the chances that the box of PMI that I had weren't up to spec? Should I try to add a regulator? Anyone? Thanks,

abartjc

[andrewnelles]

odd, maybe bad paint to barrel match?

[craltal]

While the balls shouldn't just fall through the barrel, the vast difference in velocities belies a deeper problem. A bad paint/ barrel match can't account for a 121 fps difference. That screams an air system problem to me. make sure everything is properly installed/ lubed, but not over-lubed.

[abartjc]

So, obviously it is a problem with my paint/barrel match. Everywhere I have read, people are recommending using the PMI premiums, that is what I am using now and the ball falls right through the barrel. What else should I try to use?

abartjc

[craltal]

correct, you don't have a good paint to barrel match. BUT there is no way that a 121 fps difference is caused by that alone. You are having air problems as well.

[abartjc]

If I am having air problems, then why do I get a +/- 8 FPS with my stock barrel using the same paint? Please provide information to back your assumption.

abartjc

[deathstalker]

Originally posted by craltal
BUT there is no way that a 121 fps difference is caused by that alone.

I used to see 80 fps differences when using some 4 year old Big Ball. It's stuff that I've kept around for "torture tests" and it works great for that purpose. I would first try paint that has a better fit. It's going to be cheaper and easier to diagnose/fix your problem than working with your air source.

[Dayspring]

If you're not using the RT chrono procedure, your chrono readings will be all over the scale.

[abartjc]

If I don't have an inline regulator, how do I set my PSI to 700? I have a preset 850PSI tank.

abartjc

[Dayspring]

You don't.

850 will work just fine.

[Plazmic]

I'm about to Chrono my new X-valve. Where do I find the RT Chrono procedure? Is it that fire, hold the trigger down, then fire again thing?

[Dayspring]

Yep.

[Enemy]

check to make sure that the lvl 10 bolt is not striking the boomstick.. that is why agd is going to threaded barrels.. i had that happen with my lvl 10 when it was sitting too low it did give me some crazy inconsistancys with the barrels.. the two ways i would check this is one try fitting the bolt in the barrel if it rubs there is a problem.. next would be to put the barrel on and drie fire the gun if you hear a ting noise then there is your problem..

[athomas]

There have been many instances of the Boomsticks not fitting mags very well at all. Maybe that is part of the problem. The biggest part of the problem is probably the paint to barrel match. If the paint is not consistent, it exagerates this problem. I would bet that some of the paint drops right through while others actuall fit or are even tight. This could cause the big velcocity swing you are experiencing.

[Plazmic]

Actually, Premiums are very consistent. So, while it may not be a perfect match, it will be the same difference in size from one ball to the next.