Power Plenum ~ Taipan Veteran

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Mr. Wall got great info. I should have stated that speed or performance will very with the plenum / tube extension. I used a longer lighter hammer spring and modified the HSTA added 2 delrin bushing on the spring to reduce the spring twang, installed a lighter valve spring, angle porting aft of VS, enlarged the double TP. If I wanted 1000fps + with 34gn I install the FX 700mm STX slug barrel. You can double stack the tube extension!


will refund if you are not satisfied with the plenum as I did with phillip even though he didn’t ask.



https://www.instagram.com/p/B5B40qvBrsc/?igshid=84klqxcbmd9n

https://www.instagram.com/p/B5DJYv4heOA/?igshid=1ctm27aa0q7ha

https://www.instagram.com/p/B4QAMP8h2vG/?igshid=rackbz8capnn

https://www.instagram.com/p/B3Zwf6xBrOV/?igshid=k6g544qk82hp

https://www.instagram.com/p/B3ZtoN5h24_/?igshid=178jlb25dnqnh
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That's some pretty epic work there Ernest! 

I would ask how you managed to get an STX liner on your Long, but I suppose it's pretty involved... Maybe you'll post a few vids on your mods. I would love to get this baby up and firing heavy slugs at 1000 fps.

@zx10wall - Thank you for taking the time to share that advice. Think I should upgrade the spring?

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If you are going to keep shooting the 33.95 at 910 or so and just increase your shot count with the extra plenum, then no, I think you are fine with the factory spring. However, if you want to shoot slugs to 1,000 fps, yes, you should get a stronger spring. 
 
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After shooting more, I learned that my Veteran’s LW barrel likes a lower speed than I was shooting. I dropped reg to 124 bar. With this power plenum and the little port job, it still plateaus at 920 fps at this lower reg setting 😊 This tells me that you can head down even lower on the reg setting. I’ve scrubbed off 26 bar from the factory 150 bar setting to 124 bar now and I am still getting the same performance.

I’ve dialed down to 880 fps with HST and the groups tightened up. At this lower speed the gun seems to prefer the 33.95 gr MK2s. I shot the gun off the reg and it isn’t climbing up in speed when leaving the reg as if the reg is set too high for the dialed speed. I’m going to leave it here for now and test more. I’m getting almost 50 regulated shots here 💪🏼
 
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Pic rail installed. Accu-Tac FC-G2 deployed. Let’s get a bit more serious with precision shall we....

1576423067_18651728945df64e9bd1c921.41638058_135555CB-20EB-4119-99C3-D8BFA3283414.jpeg

 
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Update on my power plenum failure. The power plenum works great does what it is designed to do. Thank you Ernest. Sorry for saying it was a waste of money. The issue was my hammer spring was not strong enough. Mr. Wall sent me a stronger hammer spring and now my max velocity with 34gn JSBs is 960 FPS. Thank you Mr. Wall.
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Thank you for letting us know, Phillip.
 
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https://www.instagram.com/p/B5DJYv4heOA/?igshid=1ctm27aa0q7ha

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Hi Ernest,

What did the lighter hammer spring do to the specific air consumption / joule?

I tried it before, but efficiënty went south.

Regards, Robert.



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I'm sure your efficiency waned with the longer weaker spring but Ernest is also using a much longer STX barrel in his set up. He's basically created a different gun. 

I'm finding that the factory reg setting is too high. If you want 60 FPE, you can get that with a regulator set to 140 bar with factory set up rather than 150 bar. 

With the power plenum installed and a mild valve port, I have the regulator at 124 bar and I am still getting a plateau of 920 fps w/33.95 grainers.
 
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I’m down to 115 bar on reg setting now. The gun plateaus at 895 fps with the 33.95 MK2s. I have it set to 865 fps. I will test you see if I’ve picked up more shots.

A good source tells me that he achieve best accuracy with their Veteran is from 840 to 870 with 840 being best.

I’ll have a Tanto delivering this week and will be using it on the Veteran. One benefit from the lower reg setting and lower speed is that the report is quieter. The Tanto will make it just right and take the under-shot current appearance away due to the reservoir being slightly longer than the shroud with the power plenum installed. 
 
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Well, the lower reg pressure (115 bar) to my surprise didn’t get me any more shots. In fact, I’m thinking less shots. I’m getting about 42 shots on a fill. I’m guessing that Taipan relies on a higher reg pressure to close the firing valve for efficiency. The valve-return spring isn’t a very strong spring. 

I’m going to raise reg pressure back to 135 bar and shoot at 880 fps with the 33.95 grainers as it was most accurate there. With this reg setting I could also shoot a 26.8 gr slugs over 900 fps. 

My apologies to any who are mirroring my modification. I’m honestly just testing and trying to determine what this set up likes. It’s been a bit different tuning this one in comparison to Crickets, Eddys, FX & Airgun Technology guns. 
 
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I am also going to do this mod for my vet long in 25. But I also bought the FX STX barrel and plan on installing it to be like the gun Ernest has. Does anyone know what the thread pitch is on the breech end of the Taipan barrel? I am a machinist and that part is no issue but I dont feel confident on the smaller parts. Like the transfer port and spring. I think there was a video on youtube where Ernest did the transfer port adjustment. Is that the same you all are doing now? Thanks

Mike
 
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i also added the plenum as well as dialed reg down to about 125. no i have no reg tester. i spoke with zx10wall and followed his suggestion. so " what happened " 

here we go 25 cal 34g JSB MK1

60 FPE / 895 FPS before 220 bar to 130 bar 30 shots after 250 bar to 105 bar 40 shots.

48 FPE / 800 FPS before 230 bar to 130 bar 40 shots after 230 bar to 105 bar 60 shots

43 FPE / 755 FPS before 230 bar to 130 bar 50 shots after 230 bar to 105 bar 74 shots

so the top end power is showing a limit so far , but the plenum is doing it's job wonderfully at 43-50 FPE with the 50% increase in shots 😃👍
 
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i also added the plenum as well as dialed reg down to about 125. no i have no reg tester. i spoke with zx10wall and followed his suggestion. so " what happened " 

here we go 25 cal 34g JSB MK1

60 FPE / 895 FPS before 220 bar to 130 bar 30 shots after 250 bar to 105 bar 40 shots.

48 FPE / 800 FPS before 230 bar to 130 bar 40 shots after 230 bar to 105 bar 60 shots

43 FPE / 755 FPS before 230 bar to 130 bar 50 shots after 230 bar to 105 bar 74 shots

so the top end power is showing a limit so far , but the plenum is doing it's job wonderfully at 43-50 FPE with the 50% increase in shots 😃👍
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Good info Marc. Thank you for sharing. 
 
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I ended up setting my reg to 130 bar. I’m shooting the JSB MK2s at 870 fps for 45 shots on a fill. With that said, I can shoot another 3 shots off reg down to 121 bar and they are just as tight as the other 45 shots. 

One pellet I tried that really surprised me was the Benjamin domed 27.8 gr. They are shooting at 940 fps and are really accurate. I’ve had these pellets sitting around for years and thought I would give them a whirl. Glad I did. 

Got the Donnfl Tanto on and it works great. I should be getting my papy_yosh biathlon lever, cheek-piece and mag holders soon and more pellets. I’m going to order up some 26.8 gr NSA slugs as well. 

What all ammo have you guys been shooting successfully?

1577491340_20019036835e069b8cbb3f55.94962325_C9BE81A6-1C82-480C-8101-C30163404610.jpeg

 
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