Velocity problems with X-Valve

[Gadget]

Played for the first time yesterday with my newly built X-Valved Mag. I'm running an AA Fred Schultz Air System set to output at about 800-850.

First problem was a leak down the barrel - fixed that by dropping from a 1.5 to 1 carrier.

Second problem was velocity - initially I had problems getting the velocity above 260, despite cranking the adjuster up a lot. Went out to play with it running very low only to find that it had jumped to 280 when I came back in from playing.

I swapped to a longer barrel and dialled it down and that seemed to be ok but I was getting a few barrel breaks, so I swapped barrels again and this time re-chrono'd at about 280 - but it seemed very inconsistant, dropping to 260 then jumping back up again - still it seemed to be working ok so I went out to play.

I got pulled for chrono on the way back in from the game and found (to my horror) that it was now shooting extremely consistently....HOT, rattling off a string of 340, 342, 344.

A 60fps jump during an 8 minute game is very worrying from a safety aspect (not to mention the fact that the penalties dropped us from first place to last).

Everytime I'd chrono the gun I managed to get it set reasonably, then I'd find that after playing the velocity had jumped up or down.

If it was just a case of being unable to crank it up high enough I'd swap to the longest Level 10 spring (currently on the middle), but this is just bizarre.

Prior to all this I had some problems with my AA reg venting out of the side hole - fixed it initally by replacing the reg piston o-ring but it started doing it again the next time I gassed my bottle up - fixed it that time by liberal oiling of the reg piston o-ring, but it has left me questioning the performance of my air system - could problems with that cause the velocity jumps I experienced?

I've actually got a PMI 3000psi pre-set reg on its way to me so I can try running the marker with that, but anyone got any other ideas on what I should be looking for?

Thanks.

[RobAGD]

Ok a few things.

Have you done a good greesing of the Reg Valve pin orings ? the level 10 bits ? If not I would think that was your biggest problem.

With lvl 10 you HAVE to oil every day of play.

Also I would make sure your not getting too much drop from the pt oring. Excess snuggness on that will cause velocity problem as the bolt speed will vary a bit and if thats not moving smoothly and consistantly your see velocity dips and spikes as the reg is venting more or less.

-Robert

[Gadget]

Thanks for the reply Rob - I'll slap a bucketload of lube into her and see how she runs.

(Hmmm, that last line sounds like a quote from a 70's porno)