Tuning Huma Regulator Setting Question

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Well, that means I need to provide a little more data on my end, as the rifle I am working with has a known issue with a heavy hammer spring. The Benjamin Akela. I have read a number of threads from shooters shortening the hammer spring, as there are no lighter replacement springs at the moment. I have also watched a youtube video of a British shooter making a custom SSG.
 
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It sounds like you are doing this work yourself. If so, and you think you have a spring problem, with no option to fix it, I say find a good source for springs and do some testing. I have a Benjamin Armada. Being a person of stupid impatience, and not wanting to wait for days or weeks to get a part that quite frankly might be right or not. I have found good success just trying different springs. I found a shorter, lighter spring with more coils per inch worked very well. I have no idea what the specs are for that spring, but it works well. No rocket science here. You might be the guy who solves the problem and maybe have the opportunity to help out some fellow shooters. 
 
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On to the regulator, I don't think you could preset a regulator for an exact FPE, only for a certain PSI, or BAR. Once installed, you will really need a chronograph to adjust to the numbers you want. My experience with my only Huma regulator has been their sticker does not necessarily jive with what you will actually get. I finally took the sticker off and figured out my own adjustments. I now know settings from 1200 - 2200 PSI. ( not a fan of BAR ). For me, I like to do my own work. The shooting just verifies if I'm getting it right or wrong. Ha. Happy shooting, good luck. 


 
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You need to find out where you're starting. Choose a set point and set the reg, say 130, it's a guess at this point. Then measure your velocity and determine the maximum at this setting by playing with HST. For maximum efficiency and greatest low ES shot count, you probably want to be around 95-97% of maximum velocity at any given set point. Don't worry if you don't have a reg tester. Your goal is a condition of balance, not a given set point. If you can't establish a workable combination, then you might need to look at hammer or spring mods, but that's generally beyond my experience level.
 
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Reg pressure will be different for each rifle.

you didn’t really mention what rifle. The pressure required is directly related to your plenum size, valving, transfer port size and barrel length 

I have a RAW and a War flex both tuned to the exact same ammo FPE

the RAW reg is 106bar

WAR flex is 70bar. 


both have hammer tuned just shy of max power for said pressure. 


 
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I'm not familiar with that rifle. From your comments, it sounds as if there is no provision for adjusting the hammer spring tension. Without having other springs to test, I'm not sure that you can do, other than adjusting the reg set point to a certain velocity. But the issue then, you don't know the balance of the tune. It could be loud, or inefficient in air use. You can probably find an acceptable set point from those measures, but it might not be at the desired power level. You could begin cutting the spring and testing, but I'd be sure to have a couple of extra springs on hand.
 
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I pulled my hammer and spring from my rifle, and verified some measurements, and from those measurements I found a compression spring supplier that has a decent selection of springs that could be used to help tune the rifle. Unfortunately, with springs that only cost $2+ each, and a supplier that requires a $40 min order, your tuning just got expensive... I'm up to $53 and that is with $11+ in USPS shipping. (group buy?)

Here is the supplier I am referring to: https://www.thespringstore.com/

Off topic; when I tried to pull the lever and bolt assembly from the rifle, at hald cocked, the hammer slipped and fired the rifle, blowing the barrel o-ring out of it. Live and learn.
 
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I'm not familiar with that rifle. From your comments, it sounds as if there is no provision for adjusting the hammer spring tension. Without having other springs to test, I'm not sure that you can do, other than adjusting the reg set point to a certain velocity. But the issue then, you don't know the balance of the tune. It could be loud, or inefficient in air use. You can probably find an acceptable set point from those measures, but it might not be at the desired power level. You could begin cutting the spring and testing, but I'd be sure to have a couple of extra springs on hand.
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My preload adjustment scew is currently backed all the way out (CCW). I have not started cutting any coils yet, as I am trying to source shorter springs that already have closed ends. The linked supplier above has some springs in stainless, but most choices are music wire springs.

My current selections revolve around a popular (cut) length of 2.5 inches, the lengths I have are 2.45 thru 2.549. The 2 wire diameters I selected are .049 & .050

I will tune with each spring size, 6 all total, and and the evaluate if a regulator is warranted.
 
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My current selections revolve around a popular (cut) length of 2.5 inches, the lengths I have are 2.45 thru 2.549. The 2 wire diameters I selected are .049 & .050

I will tune with each spring size, 6 all total, and and the evaluate if a regulator is warranted.

My preload adjustment scew is currently backed all the way out (CCW). I have not started cutting any coils yet, as I am trying to source shorter springs that already have closed ends. The linked supplier above has some springs in stainless, but most choices are music wire springs.
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Sounds like an interesting plan. I think you will find, a regulated tune will give you more shots in the most consistent area of the shot count. It will avoid having to closely watch fill pressure to stay within a certain velocity range. If you are willing to manage it, there's no reason that an unregulated rifle cannot offer top performance, and without the added complexity of a regulator. But, I think most folks find that the easier operation of the regulated rifle offsets its potential issues. 
 
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I ordered a Huma regulator just now, and asked that they provide a recommendation for reg setting based on my rifle specs, and what fpe I wish to tune to. I imagine it will be set to 1340BAR, for no other reason than that seems to be about the common spec.

On another note; I pulled my barrel out to reinstall the internal barrel o-ring that blew out last night, and in doing so, cut flat spots on the two outer b arrel band o-rings. I thought that maybe I did not back the retaining grub screws that hold the barrel in place, but they are back out so much, they nearly fell out... And oh yeah, I pulled out my custom single shot tray, and the detent ball shot across the room, never to be seen again... 
 
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Dang! Ordered my Huma on the 4th, and received it on the 7th from Germany, not bad at all. The reg came pre-set to 130 BAR. No word on the springs yet.
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Don't be surprised if you need to make some further adjustments. The pressure scale on the Huma reg is a rough indicator at best, notoriously inaccurate. But, it's a benchmark, and if you need to go up or down, you are at a known starting point.
 
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