"jking"James, I didn't mod the valve in mine at all. I don't guess I even know what they are, lol. I'd just try to lighten the hammer and I think you'll get some nice results or at least it would get you in the ball park of something that might only need tweaked.
jimmy
I agree especially since you are willing to tune to 30 fpe. As far as lightening the hammer its really hard to say if you need to get it as low as it can be. It really depends on where you end up setting the regulator. I believe motorhead lowered his hammer weight around the 10 grams I did and used a fill of 140 bar maybe 145 bar. Based on what you want to tune for I would say you will end up somewhere around that 10 grams.
When you tune a regulated pcp you want to be on the knee not the plateau. If you tune to be on the plateau the rifle will be less efficient. The knee is where you are just opening the valve enough to get the required air for the least amount of dwell needed for the velocity you want. So basically a partial valve lock for the shot cycle and exactly what happens on the first shots of an unregulated pcp bell curve tune. The hammer has just enough force to sip the perfect amount of air from the regulated chamber.
Heres a break down of how I tuned mine:
After installing the regulator I shot 3 shots over the chrono. I then added a small shim to my hammer spring and shot 3 more shots over the chrony. The first 3 shots are to establish a base line. You add hammer spring pre load by adding a shim and the purpose of that is to tell you if you are on the knee or the plateau of the regulator setting. The plateau is exactly what it sounds like and is the point where you dont gain any velocity by adding hammer force.
example of what you get if you are on the plateau:
regulated with stock hammer pre load - 890 fps
after installing shim - 890 fps
example of what being on the knee will look like:
regulated stock hammer pre load - 890 fps
after installing shim - 910 fps
You will most likely be on the plateau with the reg set at 135 bar and everything else stock but it doesnt hurt to check it and saves you guessing. Mine was on the plateau at that reg setting and everything stock. I had to lighten the hammer about 6 grams before I seen any drop in velocity. So it was pretty high on the plateau and a huge air hog. Mine only needed the 10 gram weight reduction and the stock hammer spring to be on the knee. The only way to know for sure is to get it shot over the chrony and do the shim test and adjust from there. If you post your chrono results we can help guide you thru the tune. Hopefully that all made sense and wasnt to long winded
