Expected joules/FPS for G-Spec HPA set-up? - Airsoft Sniper Forum

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Old 01-11-2020, 10:13 PM   #1
Young Gun
Join Date: Jan 2018
Posts: 10
Expected joules/FPS for G-Spec HPA set-up?

Hey guys! I recently installed a G-spec barrel on my Wolverine Bolt set-up, and I'm only seeing a max of 2.91J with .45s.

My site actually measures based on FPS, with a limit of 450 for snipers with .28g BBs. If I use .28s to measure, I'm only getting 2.08J, or exactly 400 FPS, 50FPS under the field limit. Am I wrong in saying this seems a little low? I'm at 190 PSI on my regulator. I know that joule creep is massive on HPA set-ups (I mean I gained an entire joule just by using a heavier BB), but I'm trying to hit my site limit, which is based on FPS.

I'm using a Wolverine Bolt with CO2 adapter.
Let me know your all's experience with HPAing such a short barrel. Thank you!
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Old 01-12-2020, 12:53 AM   #2
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Location: UK
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I can't speak from experience but that does sound low. Check your seal (finger over end of inner barrel) to check for leaks would be first place I'd start.
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Old 01-12-2020, 05:29 AM   #3
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Location: PA, US
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I use a few g spec barrels with Wolverine bolts. The higher air usage is kind of a pain, but if you have a good size tank it’s not that big of a deal, because you’ll still have plenty of air. My sites limit is 370 fps for a .48, which is right around 3j. With a 300mm g spec Edgi 6.00, my regulator needs to be around 180-185 to achieve that. For a .45 you should have a little more energy at your regulator setting. But it may depend on your barrel/bore.

Like mentioned above, definitely check your air seal. Make sure the outer barrel is threaded in enough to have the nozzle in the bucking. Also, an AA hop chamber along with a teflon seal is very good. The AA chambers have a good seal but you can still teflon seal the bucking along with the guide piece it has. Other than that, it’s mainly a short barrel thing.
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Old 01-12-2020, 11:01 AM   #4
Jr. Sniper
Join Date: Oct 2016
Posts: 112
The Bolt-M doesn’t seem to have this issue, so it seems to be a reservoir size issue. It’s a shame because a check valve “air saver” and having no moving parts during the shot are both awesome ideas.
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Old 01-13-2020, 10:28 AM   #5
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I wouldn't quite say joule creep on HPA is massive, personally - I'd reserve that word for systems designed to joule creep - because it pretty much doesn't matter how you tune the system (short/med/long barrel, low/high PSI, low/high Air Saver tune), you'll always get almost exactly +1.5J moving from a .2g to a .69g BB (my tests mixing the previously-mentioned variables showed a high of +1.60J creep and a low of +1.46). Clearly though, this does imply HPA systems seem to VERY consistently joule creep a significant amount (at least the Wolverine Bolt). However "massive" is what you get when you actually try to joule creep- by altering the output pressure curve (this is still possible with HPA systems like the SDiK or Bolt M- by only 'leaking' pressure at initial trigger pull before releasing the reservoir at maximum).

I have a ton of data on joules given barrel length, PSI, Air Saver tune, and BB weight, so I'll let you know what I'd expect to see with your setup when I get home- is your Air Saver tuned stock? I will say though, if you're already seeing a joule of creep up to .45g, I'm not sure there's a problem (or if there is, it's probably present at both data points you're using to calculate creep).


Last edited by MagicMarker; 01-13-2020 at 05:07 PM.
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Old 01-13-2020, 05:22 PM   #6
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Alright OP here's a couple example systems close to yours and the joules they generated:

200 PSI
300mm x ?mm
.69g BB
Low output volume -> 2.871
High output volume (stock Air Saver tune) -> 3.66J

218 PSI
300mm x ?mm
.45g BB
Low volume output
-> 3.13J

The barrel used in both cases was at least 6.03mm, but may be wider actually... The power you're seeing doesn't seem too unreasonable.
Barrel length has a significant effect on power for the Bolt- 300mm is quite short.

Last edited by MagicMarker; 01-13-2020 at 11:52 PM.
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