Tuning Huma-Air Regulator in Benjamin Akela - Hammer and Power knob settings?

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travasky

Member
Jun 2, 2021
15
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AZ, United States
 

I have installed a Huma-air reg. for the Benjamin Akela. Consistency is very good but air consumption seems a tad high. I am working to increase shot count / increase efficiency.

I do have a few questions in regards to this:


1. There is very little adjustment on this rifle for hammer spring tension. About 2.5-3 turns total on the adjustment screw which is very fine pitch. Over the chrono I'm not seeing any real FPS drops which leads me to believe I'm still too high on the tension. What might you suggest? Clip a coil? Swap the spring altogether? Make a custom hammer? I have a full machine shop so making parts is not an issue.


2. Also, this rifle has an external power adjustment knob. Should it be set to maximum when used with the regulator or some other position? Does turning the knob down, restricting gas flow through the transfer port, decrease air consumption? The knob just seems like yet another variable and I'd like to have as few variables as possible. Id like to know how this might affect the overall consumption so I can pick a spot and just leave it.
 
When you put a reg in a gun that came unregulated there is a lot more to it than put the reg in and live happily ever after. You will want to run your power knob wide open, possibly make it even larger. Basically everything in the gun is now wrong since you put a reg in it and are now operating at a much lower consistent pressure. Your hammer is now too heavy and hammer bounce is more pronounced. Both are wasting air. Your spring is also too heavy. I will provide a link to when I regulated my Kral. It now performs like a regulated gun should but it took some work.https://www.airgunnation.com/topic/kral-jumbo-project-some-observations/?view=all
 
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That thread was extremely useful. While not exactly the same mechanically your mods got me pointed in the right direction.


I made a custom spring guide and was able to reuse the stock spring. I set the spring preload such that the hammer free flies the last 1/8” to the valve. It’s amazing how much quieter the rifle is with the absence of excess air. The rod is a M8x100 bolt with the head turned down. The end cap is some 4140 with a delrin guide.

I did have to modify the back of the stock to accommodate the bolt stroke.

I didn’t lighten the hammer. It weighed at 46 grams stock.

A157BEFC-E9A7-4DE2-8561-6A27818FA422.1622769823.jpeg


With JSB 15.83 I’m hitting 840 with the reg set to 135 bar. 60 full power shots before going below 135 bar. That’s sub 20 psi per shot. ES of 18, SD of 3. I’m not sure what people consider “good” or “excellent” but this is a massive improvement over stock.
 
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Hi travaski - 

I'm hoping you can help me with 2 questions. You were able to get the Huma-air regulator installed on your Akela so I anticipate you had no trouble getting the Air Cylinder (along with the Akela valve body) out of the action.

QUESTION 1) How did you get the air cylinder off the gun? I realize the trigger assembly needs to be loosened but exactly how did you hold the tube to unscrew it and is there any other things that need to be loosened such as setscrews that keep it from turning? The items that screw into both ends of my air tube are so tight that it feels like there is lock-tite on the connections and I'm concerned I'm doing something wrong with the amount of force I've already tried applying to remove the tube. Based on everything I read and what I've seen with my gun, all the Akela's are not assembled 100% exactly the same. Perhaps there's no torque spec on these two connections and they're over-torqued and that's why I can't remove the tube.

QUESTION 2) What method did you use to add the extra breathing required with this regulator? I've read 3 different methods (A) machine a flat on the valve body threads (B) don't fully tighten/seat the pressure tube against the valve body (C) add a notch or hole to the regulator end of the tube.



Thanks,

ekurek
 
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First, loosen the air pressure gauge a slight bit until you hear the air escaping. Take the adjustment nut off the trigger rod. Loosen the tube clamp, remove it from the tube. There are 2 set/grub screws holding the valve in the receiver, just back them off a couple turns and remove the tube from the receiver. Both ends of the tube have caps that a 1.250" open end wrench will remove, just remove the valve. If needed used a hair dryer on the valve cap, the threads are about an inch long. The Huma regulator number is 1169, the plenum is 1265.

Put some tape on the flats on the valve body so the wrench doesn't mar the finish.
 
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Travasky, Did you have any trouble w/leakage around the Huma regulator? I can't get mine to seal. Huma says tube problem. Looking in the tube there is a mark that looks like a seam the full length from welding/extrusion process and I can feel it w/my finger. It's not rough, just uneven. I'm working at polishing it smoother but I have a slow leak out the vent I made as per instructions.
 
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ekurek said:
Hi travaski -

I'm hoping you can help me with 2 questions. You were able to get the Huma-air regulator installed on your Akela so I anticipate you had no trouble getting the Air Cylinder (along with the Akela valve body) out of the action.

QUESTION 1) How did you get the air cylinder off the gun? I realize the trigger assembly needs to be loosened but exactly how did you hold the tube to unscrew it and is there any other things that need to be loosened such as setscrews that keep it from turning? The items that screw into both ends of my air tube are so tight that it feels like there is lock-tite on the connections and I'm concerned I'm doing something wrong with the amount of force I've already tried applying to remove the tube. Based on everything I read and what I've seen with my gun, all the Akela's are not assembled 100% exactly the same. Perhaps there's no torque spec on these two connections and they're over-torqued and that's why I can't remove the tube.

QUESTION 2) What method did you use to add the extra breathing required with this regulator? I've read 3 different methods (A) machine a flat on the valve body threads (B) don't fully tighten/seat the pressure tube against the valve body (C) add a notch or hole to the regulator end of the tube.



Thanks,

ekurek
Click to expand...
 
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Vetmx said:
When you put a reg in a gun that came unregulated there is a lot more to it than put the reg in and live happily ever after. You will want to run your power knob wide open, possibly make it even larger. Basically everything in the gun is now wrong since you put a reg in it and are now operating at a much lower consistent pressure. Your hammer is now too heavy and hammer bounce is more pronounced. Both are wasting air. Your spring is also too heavy. I will provide a link to when I regulated my Kral. It now performs like a regulated gun should but it took some work.https://www.airgunnation.com/topic/kral-jumbo-project-some-observations/?view=all
Click to expand...
 
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