Help tuning a marauder .177 with huma regulator

[FuzzyGrub]

Hi, I brought new reg (huma-air) . I had no knowledge regarding tuning, it's my first time.

It has been quite a while since I regulated mine. From memory:

- Open valve exhaust to 0.140"

- Open transfer port to 0.140" or buy the TP for the 25 cal Mrod, which is 0.140"

- Open barrel port to 0.140"

- Regulator set to 1600psi



Now, my guess is that the OP's erratic issues seen above were related to the very heavy hammer. The oem hammer is heavy for 177 cal, and way too heavy once you regulate it. I used an 18g MDS hammer, but not sure where you would get one these days. Going to the lighter hammer also requires a lighter valve spring. I think Hill still sells those. He might have light weight hammers too. If you stay with the OEM hammer, also keep the heavy oem valve spring. In that case, you might try an O-ring buffer to prevent excessive dwell of the valve.

As far as the adjustments. The velocity screw should be 4.5 turns out from full CW. The adjuster is under the jam nut.

Throw and hammer adjustment will depend on what you used and final tuning. Tuning is not a cookbook, and takes some of your time.



PS: I forgot to add that I get 80 shots on reg @ 18.5FPE w/10.3 AA pellets. I think my Es was 10, but I would have to go find the old data. This was pre-SSG or similar debounce devices were openly discussed. With SSG, would expect that to be closer to 100 shots.

 

[DJinAZ98]

How sure are you about the actual reg setting? Are you getting that from a gauge or is that what the reg is set at? I installed a Huma reg in my .22 Armada with its own gauge. The two did not agree. The actual reg setting was way off what the pressure turned out to be. After 4 tries to get the reg pressure where., I wanted it based on the scale on the reg., I accumulated enough data to ignore the scale, and set the reg where I thought my target pressure would be. I finally got approx. 1700-1750, PSi. I am not a fan of BAR gauges as BAR is not as familiar to me as PSI. , and I think BAR readings are not as fine tuned as PSI. I also installed a fill pressure gauge into my marauder tank so I can track how many shots before pressure equalizes. I have changed springs in trigger, hammer spring and internal valve spring, all lighter than stock , but not from a known source, just something I am trying to do on my own. It all seems to be working together pretty well. I am no air rifle expert, but I really enjoy working on mine. My chrono readings are way more steady than stock and with the 2 inch longer L/W barrel, accuracy is better as well. It is not a top comp gun, but making it better, as well as myself has been a blast. I am getting about 50 shots at about 870 FPS and my air valve is set at 2.0 - 2.5 out. It is my opinion that while the reg controls pressure, it does not control volume, which controls velocity and air use as well. Power v shot count. I only use mine for matches that require 20 FPE limit so far. Soon to do some extreme F T and B R. 

Just have fun and if you like to tinker, this will keep you plenty busy, If you have lots of cash, you can get that baby pro tuned and upgraded more than you can imagine. 

Good luck and shoot straight.