Whoa whoa whoa! I've not posted here in a while!
Anyway, I bought a ULT + Xvalved mag about 6 years ago then stopped playing without ever really using it so it's been sat in a kitbag since then. Now I've started to play again, I dug all my kit out and went about trying to get it to work; I aired the thing up and to my delight it shot and sounded relatively healthy all things considered, however shooting it at anything approaching rapid fire causes it to cough and splutter and over the chrono, the velocity was all over the place, even when shooting very slowly.
Can you nice chaps help me out any maybe suggest what may be going on?
Some other stuff that might help:
* My only HPA bottle is on Guerilla Air Myth which according to the website outputs ~650psi as standard, this sounds a bit low for a mag
* The RT effect (the pushback on the trigger) was very weak making it extremely easy to shortstroke
* I put a classic lvl10 mag valve in there which shot just fine, so I'm p confident it's an issue with the xvalve rather than the body/grip/rail
* I've taken the valve and ULT assemblies apart and they all look correct from what I can see, unfortunately I've either lost (or never had) the parts kits so I've been unable to test stuff out by fiddling with various springs/shims/oring carriers