Chris - Please do keep us updated. Especially about loudness and accuracy at 60 FPE.
Well, here is the first installment on the journey.
Previously I had changed the barrel for my WC MK3 BT VP to a 500mm .25 cal barrel. I also switched out the aluminum bottle for a 480cc CF bottle and replaced the .22 cal pellet probe with a Huma .25 cal pin probe. This gave me 863 FPS (42 FPE) with the FX 25.4 grain pellets with the reg at 100 bar. Not particularly impressive. I raised the reg to approx 110 bar and the velocity dropped to 763 FPS! Obviously, the reg pressure was too much for the hammer so the valve was not opening enough.
Today, I made the following changes (1) Maxed out the hammer spring adjuster and, (2) Installed the hammer weight from the FX Wildcat/Maverick Slug Power kit. After reassembling I tried to raise the reg pressure some more. Nothing doing, it wouldn’t change! The velocity did increase however, back to about 870 FPS. At this point I should mention that my 500mm barrel has the old style Transfer Port with a single round hole.
OK. Obviously I have a reg setting problem, so I need to determine the 1st reg pressure. Imagine my surprise when I turn the screw for the second reg counter clockwise a couple of turns and the reg pressure on the gauge doesn’t change.Could it be? Yes, the 1st reg was set at an incredibly low pressure, probably 110 Bar. So, now I need to take the stock off so that I can adjust the first reg.
As I increase the first reg oressure (counter-clockwise) I hear the telltale hiss, and the pressure gauge starts to rise. I raise the 1st reg to about 160 Bar. (Did I mention that my next purchase will be a decent gauge - probably a Huma/Wika - so that I can actually read the damn thing). Then I degas by removing the bottle, dry fire and listen to the air bleed out of the plenum until the gauge reads zero. Next I turn the second regulator screw clockwise until I feel some resistance. Then I go back counter clockwise for a half turn or so. Screw back on the bottle and, voila, my second reg reads about 40 bar. I then adjusted the second reg up to approximately 130 bar and now, finally I am good to go for the moment of truth.
The results are interesting!
FX 25.4 grain pellets; 1st Reg 160 Bar; 2nd Reg 130 Bar; Hammer adjustment maxed.
HW Shots High Low Avg FPE ES SD Wildcat MK3 BT Compact 7 12 984 979 982 54.4 0.5% 2.1
Wildcat MK3 BT Compact 6 10 995 984 989 55.2 1.1% 3.8
Observations:
(1) Obviously the gun had been set up with a very strange tune from Utah Airguns, one that was clearly set to maximize shot count and not power, or not even to really utilize the benefits of the new BT dual regulator/large plenum setup
(2) The new tune is not complete. The fact that I get a higher FPS from position 6 than from position 7 show that the Valve is slamming closed on P7. This I either need to adjust the hammer spring adjuster downwards a bit, or raise the reg pressure some more. In any event I’ll play with it until I get a nice (downward) FPS gradient when I change the wheel from 7 to 6 to 5…
(3) The gun is a little louder now, but not a material difference to my ears.
(4) I should have no trouble getting well over 60 (and probably over 63) FPE when I use 34 grain pellets. I might also get some gain from switching the Transfer Port out with a Huma slug port.
That’s it for tonight. Tomorrow I will shoot the 34 grain pellets to see what kind of power I get. If I am still not getting a gradient on the wheel as i go down from 7 to 6 to 5 I’ll either adjust the hammer spring preload down a little or raise the reg pressure a bit, so that position 7 is indeed the highest.
Chris