Have you considered filling it with Co2 instead of HPA? There are some really nice ten-meter guns set up that way. That might make it a little easier to regulate as well.And good on ya for getting your daughter involved in shooting. Hoping she excels at it.Cheers,J~
After some research, this is what I'm thinking. Change the hammer spring to shorter, stiffer spring, but overall less tensionPossibly lighten the hammer, or make a new one out of peek? Make a smaller transfer port out of glass filled delrinMake a new poppet out of glass filled delrin. I was originally thinking maybe peek, however with the low working pressure of 2k psi max to start, and possibly going very low, peek may not seal. Would glass filled delrin be the best option for a new poppet? With all these mods, I think I could get a pretty efficient 5-7 ft-lb .177 gun that would get a ton of shots off a fill. And, be alot cheaper than buying a precision 10 meter gun. Thoughts? Thanks!
Not that I am trying to talk you out of your project...But have you looked at a Beeman AR2078-A or-B?While they are Co2 guns, if her match is indoors, it shouldn't be an issue. With 2 carts they get more than enough shots to complete a match and they are much closer to a true 10m gun out of the box than a QB.
Regarding glass-filled Delrin…depending on the percentage of glass fill, it very well may have a hardness and compressive strength comparable to PEEK. Meaning similarly unforgiving of surface imperfections and the potential for having a slow leak at low pressure. FWIW I’ve managed to get PEEK to seal fine at CO2 pressure (~800psi), and sometimes even hiss-free when filling from zero pressure with a hand pump. Not from an as-machined surface straight off the lathe but by dressing the sealing face against sandpaper in a simple jig, just a flat piece of material with a hole drilled for the stem to pass through. Copied and pasted from a previous topic: I used a hollow punch to knock out a bunch of holes in a piece of 220 grit sandpaper. From there, it's just a matter of putting the stem through the sandpaper and the wood block, and grabbing the stem from the back side with a drill and spinning it against the sandpaper to smooth it out. If you color the face of the poppet with a marker, you can monitor for the low spots as you go. It will be obvious when you've done enough because the marker will be completely removed. Lastly, it's a good idea to lightly lap the poppet to the valve to ensure they mate fully. Again, color the surfaces with a marker and spin them together with a mild abrasive like J-B bore compound or a metal polish. When both surfaces develop a neatly polished ring where they meet, you're done.