Here's a quick writeup of what I did to make my mQ valve fit my slightly out-of-spec Turtle body.
The problem: The valve body -- the front portion of the valve housing the poppet -- would not fit all the way into the gun body. It bottomed out on a shoulder of metal just before the jam nut threading, so the exhaust holes would not like up with the valve set screw hole and thus the transfer hole to the bolt. The front o-ring did not fully clear the set screw hole, so it could not have worked despite the misalignment.
Apparently on some guns this metal shoulder is too far back and the valves were designed for a certain specification.
The solution: There are several solutions to this problem. The factory-suggested solution is to have the body drilled out a little more to move the shoulder further in. This requires a drill press and a large drill bit (the size of the lower tube).
The valve body could be turned down at the "flange" that bottoms against the shoulder inside the body. This would allow the valve to slide past the shoulder and sit deeper in the body.
A custom valve body could be made (or released by PBX) but that is more work that necessary and a factory release is not likely.
My solution: I chose to try to turn down the valve body, by hand. Yeah, by hand. Ideally one would use a lathe for this but anyone with such access could probably drill out the body without too much trouble.
But I felt that hand-sanding might work, as long as I was careful. It was the only option open to me at home at night, and the keen cockerholic (that sounds dirty) doesn't suffer a non-fitting mQ valve lightly.
Now if you choose to do this fix if you have the same problem, I have to add a disclaimer here. I was fully ready to accept the possibility of ruining the valve body in this process. YOU SHOULD BE TOO. I contacted PBX and they will sell replacement parts to prior owners. They reiterated that I should probably fix the body. But I needed it fixed NOW. :twisted:
Anyway my suggested process is to use coarse sandpaper (80 or coarser) to gradually sand down the outer edge of the valve body flange. Before you start, wrap some easily removable tape around the front of the valve, leaving only the flange exposed. This will prevent scuffing and save your fingers from the edges of the exhaust holes and the o-ring seat. It will also make the thing easier to turn by hand. Remove the poppet and set it aside.
I cut the sandpaper into strips to wrap around the outside of the flange, and turned the valve body both continuously in one direction and back and forth, to keep it even. Be prepared to do this for a LONG time, you want to remove a little at a time and check it often. Remove the tape and wash the body out before each check, to keep any shavings out of the body.
You want a fairly tight fit. Eventually the valve should seat properly. You an finish with diminishing grades of sandpaper and polish if you like.
During the process, be careful to sand only the outer edge of the flange. Make especially sure you don't damage the poppet bore in any way.
When you are done, lube, reassemble, and you should be good to go. Some might say this is a "ghetto" fix, but hey, my mQ is installed and working, and I didn't have to pay anyone a cent.
Here is a photo of the area I sanded, the outer edge of the flange. Note that this is for reference only, you MUST disassemble the poppet assembly before sanding!
