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(almost) finished with my airforce build!

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sticman77

sticman77

Member
Jul 31, 2019
639
29
ID, United States
thanks @Raden1942 and others for the help with this!

after spending some time with a huben this year, i decided i didnt like the bulkiness of the bull pup platform, and also didn't like the complexity of the huben and wanted a platform i would be able to work on myself with more confidence.

finally finished up this build started with an escape ul .22. added a TT CF bottle, altaros reg, and pcp tunes valve. weighs in all setup with sling, donnyfl, scope, etc. at 6.5 lbs. had a bigger scope, but decided a little 3-9x would be strong enough for what it would be used for.

currently adjusts from 15-40 fpe using power wheel. waiting on heavy hammer w/slap mod from TT to shift that scale up a bit, hoping the scale will shift more to 25-50 fpe (i assume there is room for improvement, as the gauge measuring the plenum pressure barely moves after a shot on max power)

IMG_7731.1606764267.JPG

 
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Sweet! This one caught my eye because I also have been eyeing there huben but feared the unnecessary complexity and went for something I understand and can work on!

I'm just waiting for a valve to get here to finish up a similar configuration that I have. I have two that I'm working on one as a modified talon p the other a talonss.


for one, I have a 12 inch 25 caliber barrel in the talon SS body with the heavy hammer, using the TalonP bottle and valve (generates at least as much power as condor valve but threaded for smaller bottle which has different thread pitch). this is a great gun - quiet, powerful and decent shot count even with small bottle. I can get over 55 FPE out of this if I use a 47 grain slug or heavier . I don't think you will get this high FPE with anything lighter than 40+ grains


My plan is to use a high output valve from talon tunes with an altaros regulator on this gun. I got the add on plenum for the regulator to increase its air capacity if needed for the high output valve. This makes things really long and kind of weird looking so I ordered a shorter high pressure tank to reduce length and 3-D printed a shell to surround that and stabilize it to prevent any flexing. I will attach a pic. The overall length is the same as a standard bottle plus regulator but without plenum. Volume of tank is either 350 or 390 cc. 

3E4122CA-23E7-4E46-813B-EB37C3178A7E.1606787618.jpeg


my other gun: I put an 18" barrel in the TalonP frame. Added a Doug Noble valve, heavy spring, heavy hammer, and a high pressure tank. That thing is POWERFUL over 100 fpe at low PW, haven't shot it above a "4" yet. Love this gun.


I hope you get as much pleasure out of messing with this as I did. Always psyched to see someone messing around with this platform!







 
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on the huben - i never did have any issues with it after i started seating the pellets correctly. it was a really fun gun, and reliable while i had it.

i really like the 3d printed cover. i am interested to know how yours performs with the extra plenum. i've been considering selling this 580cc bottle, and going with a shorter one so that i can chain this on:

https://talontunes.com/shop/talon-tunes-tank-adapter/

to help with the cheek placement, but also add a bit of plenum. if you are getting good results, i'll probably proceed.

at this point i probably have as much in it as the original gun. but i am enjoying the process and how light i've been able to keep it. i feel the foregrip is in an awkward position for me, so i just removed mine and enjoy the hold much better.
 
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That's one heck of a plenum.


just finished this up. A 25 caliber talonss with TalonTunes sho valve and altaros regulator with plenum and medium volume 4500 psi aluminum tank on the back. Will fire the first shot with this combination in about 5 minutes.

0A7830FC-D0AE-427D-8164-7CF6061CDDE6.1606863855.jpeg
Click to expand...

very interested in these results!

i'm not sure if this is old documentation, but i only fill the bottle to 250 bar, based on this:

https://www.altaros.cz/en/airforce/75-5983-airforce-condor-airgun-regulator.html

"According to the type of bottle can be pressurized up to 250 bar (3600 PSI). After filling to set pressure drain air from hose and disconnect paintball coupler."



not sure if this was just written in the past before 300 bar bottles were more commonly available
 
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I will not pump above 3500 psi for sure. Appreciate the heads up.


so I fired off a few shots. The talonss baffles do a great job of keeping it quiet so the only sign that something was different from the previous valve I was using was the extra recoil, which is noticeable. I tested against an extra piece of bamboo floorboard that my talon p can not quite penetrate at 50 fpe. It is very hard dense material... much harder to penetrate that 3/4" plywood.


At "1" on the PW penetration was comparable to talon p at 50-55 fpe, almost exiting the back but not quite. 


At "6" on the PW it shot straight through - guessing up around 70 fpe or so. Will test with a chronograph later... it was acting odd last time and I haven't used it in a while.


Very pleased with the power with this combination - especially with the 12" barrel.





67FE9911-88DF-4912-9629-37E53952D7F9.1606870018.jpeg





 
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I will not pump above 3500 psi for sure. Appreciate the heads up.


so I fired off a few shots. The talonss baffles do a great job of keeping it quiet so the only sign that something was different from the previous valve I was using was the extra recoil, which is noticeable. I tested against an extra piece of bamboo floorboard that my talon p can not quite penetrate at 50 fpe. It is very hard dense material... much harder to penetrate that 3/4" plywood.


At "1" on the PW penetration was comparable to talon p at 50-55 fpe, almost exiting the back but not quite. 


At "6" on the PW it shot straight through - guessing up around 70 fpe or so. Will test with a chronograph later... it was acting odd last time and I haven't used it in a while.


Very pleased with the power with this combination - especially with the 12" barrel.





67FE9911-88DF-4912-9629-37E53952D7F9.1606870018.jpeg




Click to expand...

those are impressive results! my setup has the "short valve" from pcp tunes that is supposed to add a bit of space for plenum. hoping i get ~60 fpe with the .22 once the heavy hammer gets here.

i may eventually purchase a 12" barrel for this. the difference in potential energy between .22 and .25 looks to only be ~ 10fpe? ...so may stick with .22. although this equation is not taking into account added friction for a similarly weighing pellet in .22 due to length:

(https://hardairmagazine.com/ham-columns/how-to-obtain-the-maximum-power-from-a-pcp-air-rifle/)

2500 * .22*.22 * (Pi/4) * (12/24) ~47 fpe (~71 fpe with an 18 inch barrel)

2500 * .25*.25 * (Pi/4) * (12/24) ~61 fpe (~92 fpe with an 18 inch barrel)



Looks like you are getting higher energy than this equation provides though. my reg is currently at 17mpa, what is yours running at?


 
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How confident are you in those equations? Seems likely to be a little oversimplified to me (could be wrong, physics can be surprising) and my results from the chronograph suggests those are off by quite a bit. I have not experienced a 92 fpe limit for an 18" barrel, have exceeded that many times. Or my chronograph is not correct. 

Am I a fool to question those (I'm new to this - are those some kind of well-established scientific formulas, or a ballpark based on some assumptions)?
 
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i am not confident at all. i am really new to tuning and working on pcp's in general. my previous experience was only adjust hammer spring, and pressure by pumping in my aspen/freedom i had.

i posted the equations (new thread too https://www.airgunnation.com/topic/25-vs-22-12-inch-barrel/#post-868258) hoping someone more experienced than myself could chime in on if they looked ok. Odoyle posted a link that seems to agree with the equation ballpark.

i would not doubt your chrono, i would doubt the limitations that equation is making assumptions on for constants, that may not be accounting for a simpler airforce type system, and/or updates to airgun technology, pellets, valves, etc. overall
 
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The Air Force design really makes it easy to tinker with. I've been enjoying shooting this regulated .25 airgun. Every shot is exactly the same it's kind of surreal. I enjoy working with the up and down of the "shot curve" on my unregulated airgun but this is quite nice as well. Don't have to think about small adjustments to hammer load to compensate for pressure changes 
 
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Did a quick test with the chronograph.

This is the regulator plus plenum plus TalonTunes sho valve and 12" .25 choked barrel. I put a restrictor in the top hat so this is a much smaller port than wide open. I'm trying to see what kind of shooting I can do with this valve tuned down for those times when I don't want to use the super high output. My goal is one or two very adaptable guns with a wide "dynamic range".


Changing the hammer spring preload did not change the numbers... which has me confused because it made a big difference when I didn't have a restrictor in there.[UPDATE: I was wrong - when I checked later with chronograph hammer load makes no difference without restrictor]. One explanation would be that even with a light hammer-spring preload, it's dumping all the air out of the regulator and increasing the hammer spring won't make a difference. But why do I get an effect when the transfer port is wide open and not when it's restricted? It's very obvious less air is coming out with the restrictor in there so it can't be emptying the regulator completely I think? I don't know...

25 grain rws super h point at ~28 fpe

33.5 grain NSA at ~30 fpe

60 grain NOE Airgun slug at ~35 fpe

47 grain MP molds boat tail (best slug by far I have shot in this barrel)~ 38 fpe



if you figure out the velocities for these they're pretty slow all in the 550 to 700 FPS range I think. I device reach out in meters/s 


That works for my garage range. Very quiet with the soundloc baffles (I drilled out some .177 baffles so maybe not as close tolerance or as quiet as a stock .25 baffle set)



I wouldn't want to use that restrictor for any outdoor seating I suppose. Next up I will test it without the insert. And I will try the tiny one just to see what happens.

I didn't do any kind of statistically significant testing but repeated shot ms had almost identical energies.



UPDATE:



I have a regulator set to 150 bar now for all of these It was at 160 for my earlier report in a different post



I took out the restrictor and it seem to add pretty much exactly 10 foot pounds. Shooting at up to 48 foot pounds depending on the slug. MP molds .25 slugs have highest energy in this barrel as usual. Seems to go through air MUCH faster, surprised a 10 fpe gain involves so much more air. 



 
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sorry if i'm just talking to myself here lol.

i e-mailed altaros about the max fill pressure, wondering if 250bar was stated due to old documentation when 300 bar bottles were not easily available.



" real operation pressure should be fine on 280bar .300bar is generally not recommended as it eliminates O-rings significantly faster on the whole airtank assembly, not only on the regulator.

Our long term test was on 250 bar. We did not have long term tests for 300 bar.
Some customers using this regulator on 290 bar , so far no one reported anything wrong"

so per altaros, 280 bar should be ok
 
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