i agree with nchittendon... the powertube isn't an issue in of itself, but a symptom of something else.

__________________
Proud Canadian Baller
Kit: A5, camo job, polished internals, 14" Smart Parts Progressive barrel. Borrowed Opsgear G36 stock. 24oz CO2 w/ remote and slide check. Neat homemade sling. MORE TO COME
Vents Goggles and Multicam

From what I gather, your power tube is cracking from the side which the hammer strikes the valve assembly? If this is the case, I doubt its the valve.

The valve itself being aluminum is going to chill much faster than the plastic when liquid co2 is introduced to it due to aluminums very conductive nature. This is going to cause the valve to contract (become smaller) faster than the plastic tube does.

Where I beleive your issue stems from is that after the plastic contracts, the inner diameter of the valve too contracts, meaning theres a smaller opening for the hammer to strike that valve. That, coupled with the fact that the hammer may have been on the large side of the manufacturing tolerace could mean that the hammer is actually 'stretching' the inside of the power tube when it enters it to strike the valve. Being that the tube is cold and brittle when this occurs, and the fact that the hammer doesnt see any co2 at all and therefore remains its original size, could split the valve in the way you're describing.

__________________
Tippmann A5, LPK!, and Egrip (APE 2.0)
PPS 12" Brass .690 - JCS RedHot modded to Gold Power Tube & Hex Bolt - PPS Stab w/ gauge & Hex-Grip - Rap4 Full Cyclone Upgrade Kit w/ Wargear Squishies - HUGE 116/3k Nitro-Duck HPA tank - Spec Ops MP5 Shroud - Rap4 Stock w/ RVA - Tacamo AK Rail - Barska 50mm Red Dot - JCS Duel Trigger

Called Tippmann and they were stumped. All they could recommend is that I lube the Valve and Rear Bolt O-rings.
So hopefully the Red Hot on the way will fix it. Thanks for all your input everyone.

What is your fps are you firing it might be that there is too much pressure on the tube or my other thought that there is something hitting the front or back for the power tube that is hitting it hard enough to crack it. well that is my 2 cents on the problem, but let me know about what the problem is

__________________
[b]I CHARGE HARD

I would try swapping out your hammer and/or valve. Its not the temperature causing the problem because you've tried 2 different HPA tanks as well. So Co2 isn't the culprit.

See how tight of a fit the hammer makes inside of the end of the powertube. Do you have to jam it in?

__________________

[quote=MDMurdock]Not much for internal mods, I polished the internals and installed a pair of TechT Squishies, oh and an E-Grip and a J&J barrel kit.
I'm really happy with my A-5 since it will do full auto at 15bps with no breaks or chops. Just really curious why so many cracked power tubes.

IF you removed too much material when you polished the receivers where the hammer slides back and forth, it is possible, tho not likely, that the front leading edge of the hammer could be grazing the lip of the power tube. The hammer could be slightly misaligned with the opening in the power tube as a result of too much clearance between the hammer and the receiver bore.
IF that is the case, your new JCS PT could be in at risk.
Just a thought. But at this point you should consider all possibilities.
Good luck with this most uncommon problem.
Scoreshot

__________________
Courage can exist only together with your fear.

[quote=scoreshot]

That's a good diagnosis. I would imagine that you would have to have taken alot of material off the receivers for that to have happened. It makes sense though.

__________________

http://www.PureExcessIndustries.com
Pure Lube Review on X7og.net

[quote=Pure Excess Industries]
Thanks Pure,
Ya, you would have to really "go to town" on the receivers for that to be the problem. LOL However, if the area where the power tube fits has also been "worked" the PT itself could also be too loose inside the bore adding to the theoretical cause of the problem.
This is a strange problem to be sure. Really can't think of anything else unless maybe he's got the wrong size o ring on the hammer. Too big or thick?

__________________
Courage can exist only together with your fear.

I don't think I took too much off when polishing. I really just took off any spray paint and burrs then brought it to a shine.
Something else though...taking out the valve from the old plastic power tube and putting it into the new red hot took some effort. Are they normally really tight?
I'm going to shoot a hopper full tomorrow and see if the red hot takes any damage. Hopefully not and I'll be gtg.

It should be a snug fit. Keep us updated.

__________________

http://www.PureExcessIndustries.com
Pure Lube Review on X7og.net