Tuning Question on installing a HUMA regulator in a p-rod

[Gary61]

I got my regulator today so I installed it without the gauge assembly. I also installed a larger Transfer port. The reg came set at 123 bar. She hit hard and by 8 shots she is running out of air. Compared to stock I get a whole lot less shots off. With that said it came a screw but for the life of me I dont see in the instructions where it goes. Maybe I'm blind or something. 

I don't have a chrono some maybe tomorrow I"ll put the gauge back in and see what she is regulated to. 

I could use some help if yall have some ideas. 

 

[1shooter]

If the screw is quite small with fine threads, like smaller than a .177 pellet diameter and about 1/3” long then it might be the one that goes in the end towards the fill port when installed. It helps??? keep debris out? I do remember it should be loose as that is the air intake for the reg. If not that screw then?

I bought my reg from a vendor and it was like four turns out of range. 

I would start by lowering the hammer spring and redo a shot string

after that get a chrono

and head the advise from other as I’m sure they know more then me

good luck

I ended up with 24 shots, a few more than the same as my bstanley tune minus the bell curve

I like/prefer the consistent shot velocity and am happy to be rid of bell curves 

 

[SqrlHntr]

The very top of the regulator should have a hex head screw, it threads in fully and then is backed out one turn. Im guessing thats the screw. Pics help. Vent hole goes at 12 o’clock. Make sure you didn’t knick the o-ring when inserting into the tube, little 1000 grit paper may help smooth off a burr or sharp edge up by the fill adapter threads. Might also want to tie a long piece of fishing line around it before you screw it back in if you haven’t already, helps with pulling it back out. Without knowing chrony numbers, I would guess two things, the set point is too high and back off the hammer spring and throw, its a different gun now with a regulator. I find the stock hammer and valve springs are too much when regulated and get better results with a lighter set, even a lighter hammer and striker. Check out Tim Hill’s parts, a #7 valve spring and a 42 hammer spring is what I like with the stock valve and hammer/striker for a regulated p-rod. https://hillairgun.com/ The headspace in a P-rod tube is small to begin with so adding a reg really depends on what your goals are. P-rods are so versatile. Btw, all my huma reg’s were off by 3-5 bar, some high, some low. Regardless, i suggest to make a mark or measure the height of a couple settings, the sticker can move or slip once silicone hits it. Chrony numbers will be key to really help you out though. 

 

[SilentSquirrel]

following with interest

 

[SqrlHntr]

Hope this helps with the missing screw. Heres a couple of pic of a new Huma reg for P-rod and another of the screw installed on a reg. Also should have 2-orings for the plenum. In terms of tuning, all i know is what works for me, which i learned from the seasoned obi-wan types here and and on older forums. Knowing shot curves of a tuned stock marauder helped me learn what part of the curve i was trying to tune to when using a regulator, i.e. the knee. Understanding that curve concept helped me with regulators more than anything. Hard Air Magazine has a fantastic technical series about pcp’s, starting with this article. Really comes down to what you are doing with it…shot count, power, es, plinking, competition. Marauders can be beasts or teddy bears and tuned to a pretty wide range of power or shot count. Also, a couple of good links that helped me learn about about marauders in general. Hope it helps. 


https://hardairmagazine.com/buyers-guides/airgun-buyers-guides/ham-airgun-technical-how-pcp-airguns-work/

https://sites.google.com/site/mymarauderdata/home ( not my site, one i found )

https://airgunguild.com/ask-bob/tuning-a-regulated-pcp/ ( same author as the hard air link)

https://docs.google.com/document/d/1Jn0RFfnH9YnFaEbT5ynizTnIyJ9DG6u5htJ_65R9P5g/mobilebasic?pli=1

marauder rifle tuning, but it helps explain the relationships of a stock setup

https://sites.google.com/site/davemyownself/25mrod-velocity-nomograph

https://www.airgunnation.com/topic/hammer-spring-vs-hammer-throw/

 

[DJinAZ98]

Hello Gary61, I have a Benjamin Armada .22. Installing the reg and getting it adjusted was not a one shot process. I installed mine with a gauge so I could see what the pressure was in real time. 1- the reg-resevior combo is pretty big so loss of volume to put air in is a reduction in shots. 2, I finally took the scale off the reg and just kept adjusting until I hit my target pressure (1700) PSI. ( not a BAR fan) Your 123 BAR is just under 1800 PSI. 

3, The larger transfer port is going to consume air quicker. IMO, the reg controls pressure but not volume. I use the stock air valve to adjust how much air flows out per shot. Mine is set @ 2-1/2 out. All my springs have been changed, lawyer spring, hammer spring, air valve internal spring, all lighter than original. Not from any gun shop, but from a large assortment of springs in my shop, so I can't give you any numbers, but it is working very well to me. I currently get about 45-50 shots per tank from 3000 PSI fill, down to equalize with reg. It shoots about 870 fps, about 18 fpe. 

Good luck, keep tinkering, you will get where you want to be. 

 

[Gary61]

Sorry for a late reply. I travel for a living and been gone for a bit. 

I put the original hammer spring back in. I have no preload on the spring nor the hammer. I average 667 fps and drop on the 24 shot. I will play with it and get to around 800 fps. I'm guessing at that point I may have to refill after the second mag. I'm looking for range and accuracy. For now I'm sticking with 14.3.