Power Plenum ~ Taipan Veteran

Well, I did it. After failing at my first attempt at making an M14 threaded adapter to mate with the stainless connectors on the FX barrel kits, I wound up consolidating both the brass inlet and stainless pieces into a single adapter. This is a pretty solid prototype that I am very happy with from what I see thus far.

The wrench that was thrown into this little project were the threads on the breech end if the FX stainless piece i had it in my mind that it was either an M12 or a 1/2-20; it's neither. It's almost an M13, but an M13 tap is too large for it. I could have probably polished down an M13 thread in retrospect, but the lead time on the die didn't align with getting a prototype made, so I had to cut the metric 1mm pitch threads on my lathe with an imperial leadscrew (thread error of 0.087%, but it's a short length so meh). The change gears make the compound slide fly really fast once the half nut is engaged, so I had to be real careful not to F it up 😂 

Anyways, the other tricky part to this was leaving just enough of a lip at the breech and a slight internal chamfer to seat the liner perfectly. I wound up using around 4 different drill bits to support my 22 cal, and the last pass was made with a modified bit to carefully bore it perfectly. I used an M14 die on the threads going into the acton, and added strategic o-rings (the last one on the breech end isn't even needed). 

My adapter doesn't need teflon tape, it's just a couple of o-rings, the sleeve, liner, and retainer. No leaks at all. I will make something to sleeve the assembly inside of the trigger housing, but for now Gorilla tape is 💯:p

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My adapter doesn't need teflon tape, it's just a couple of o-rings, the sleeve, liner, and retainer. No leaks at all. I will make something to sleeve the assembly inside of the trigger housing, but for now Gorilla tape is 
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:p

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Very nice. You plan on selling these adapter "kits?"

Yeah, my next step is getting them made up in stainless. I just don't have a quick way of making them, nor do I have thr time so I need to outsource. None of the shops in town that I showed this to want to take it on, but I have some leads from them on ones that will. If they say no, then I'll have to CNC, but either way I'll have some.

Freaking bravo @mtnghost
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Thank you sir! It was a LOT more work than I thought 😂 
 
Nice work MtnGhost. I've been following this thread and decided to pick up a veteran as my first high end gun. Is there a specific reason why you guys are choosing an FX brand barrel over another company barrel to fit to the gun? I don't see me modifying my rifle barrel right off the bat, but adding the plenum and a donnyfl is very tempting.

Well, the reason that I did this mod was because I wanted better precision / accuracy with JSB Monsters and slugs. As Ernest kind of said earlier in this thread, there's a "luck of the draw" aspect to barrels. Unfortunately my Taipan barrel was not a winner in that regard 😭


👊 😎 
 
Nice job Ghost! I do want to stress to AGN members that ALL BARRELS, be it LW,, FX STX, and others have varying degrees of barrel excellence. As Ernest also said, even the FX STX liners some are better than others, just as the case with LW. It’s been my experience that most are “good”. Some of any type “not so good” and some you win the barrel lottery and they are amazing. I have three guns with amazing barrels (.22 LW - EDGun R3 Long, .22 CZ - Cricket mini Carbine, and .30 FX ST - FX Bobcat). All my other guns have good barrels, not bad or great. The take away for @terrible_t is to give your Veteran a chance before you even think of a different barrel. Your LW barrel might just be amazing. 
 
In my case I have a 25 Taipan Vet and have a 700mm STX barrel left over from when I had a 25 Impact. As long as I can swap things back to stock down the line, I want to see what the gun will do.

Sorry, if I missed this but my questions is if there's anything permanent we are doing to the actual "chassis" ) of the Taipan doing this mod including the barrel swap that would prevent me from being able to swap back to "stock" form if I wanted to in the future?



RJ
 
In my case I have a 25 Taipan Vet and have a 700mm STX barrel left over from when I had a 25 Impact. As long as I can swap things back to stock down the line, I want to see what the gun will do.

Sorry, if I missed this but my questions is if there's anything permanent we are doing to the actual "chassis" ) of the Taipan doing this mod including the barrel swap that would prevent me from being able to swap back to "stock" form if I wanted to in the future?



RJ

No. 
 
That is a very nice job, MtnGhost!

Nice job Ghost! I do want to stress to AGN members that ALL BARRELS, be it LW,, FX STX, and others have varying degrees of barrel excellence. As Ernest also said, even the FX STX liners some are better than others, just as the case with LW. It’s been my experience that most are “good”. Some of any type “not so good” and some you win the barrel lottery and they are amazing. I have three guns with amazing barrels (.22 LW - EDGun R3 Long, .22 CZ - Cricket mini Carbine, and .30 FX ST - FX Bobcat). All my other guns have good barrels, not bad or great. The take away for @terrible_t is to give your Veteran a chance before you even think of a different barrel. Your LW barrel might just be amazing.

Thanks! To @centercut's point, definitely give that barrel a chance. Usually if I get a barrel that is just throwing a random flyer, I know that it's a diamond in the rough. Now if there printing wild 3-4+ inch groups at 100, I wouldn't waste more time, and then it's probably time for plan B lol
 
With 2 power plenums added and the FX barrel system w/700mm liner, I needed to lower my reg as I was getting mondo power at my current 142 bar. 

Problem I experienced when previously lowering my reg to 130 bar or lower, was that I found my efficiency went South. I contributed this to the weakish factory valve-return spring. So, I shimmed the spring to stiffen the tension using two small washers. I placed these on the end of the assembly closest to the c-clip; over the spring guide and under the spring. Pictures and specs of the washers are below. Again, I utilized 2 of these washers.

I lowered the reg to 115 bar and dialed for 910 fps average with the hammer spring adjuster. Here is a full shot string from a 250 bar fill. I’m pretty happy with it. It dropped off after the 47th shot averaging 62.4 FPE. 

Created: 01/25/20 08:31 PM
Description: .25 Veteran
Notes 1: FX 700mm
Notes 2: 
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 0.046
Bullet Weight(gr): 33.95
Temp: 61 °F
BP: 1017.87 inHg
Altitude: 120.00
# FPS FT-LBS PF
47 909 62.30 30.86
46 902 61.34 30.62
45 903 61.48 30.66
44 906 61.89 30.76
43 903 61.48 30.66
42 900 61.07 30.56
41 914 62.99 31.03
40 906 61.89 30.76
39 911 62.57 30.93
38 915 63.12 31.06
37 914 62.99 31.03
36 910 62.44 30.89
35 904 61.62 30.69
34 902 61.34 30.62
33 914 62.99 31.03
32 912 62.71 30.96
31 908 62.16 30.83
30 912 62.71 30.96
29 906 61.89 30.76
28 912 62.71 30.96
27 914 62.99 31.03
26 908 62.16 30.83
25 912 62.71 30.96
24 912 62.71 30.96
23 910 62.44 30.89
22 911 62.57 30.93
21 911 62.57 30.93
20 912 62.71 30.96
19 908 62.16 30.83
18 904 61.62 30.69
17 913 62.85 31.00
16 908 62.16 30.83
15 901 61.21 30.59
14 907 62.03 30.79
13 907 62.03 30.79
12 911 62.57 30.93
11 908 62.16 30.83
10 906 61.89 30.76
9 909 62.30 30.86
8 913 62.85 31.00
7 899 60.94 30.52
6 914 62.99 31.03
5 918 63.54 31.17
4 901 61.21 30.59
3 915 63.12 31.06
2 907 62.03 30.79
1 906 61.89 30.76
Average: 908.7 FPS
SD: 4.6 FPS
Min: 899 FPS
Max: 918 FPS
Spread: 19 FPS
Shot/sec: 0.0
True MV: 910 FPS

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To compliment what Derrick is showing with the washers - it's tempting now to mill out the floating metal spring guide and tap some threads in place to add an adjustable length spring guide using a slightly fatter grub screw turned down to 4mm on the valve side (as the new seat for the valve spring). I was suppose to get more aluminum Friday, but I'm getting too impatient and might just do this today hahaha
 
Forgot to update this thread. I did a couple of additional mods recently:

  • Made another prototype valve pin using (Ketron) PEEK, 8mm OD and less material than the first
  • Made a PEEK valve spring seat to add a total of 3.1mm of additional valve spring tension over the factory length
  • Installed my 600mm FX barrel kit with slug liner A, borrowed from the FX Crown that I bought off of @bob_o
  • Re-added the Taipan LDC with a 13.1 x 1.6mm o-ring sandwiched between the Crown kit's shroud shaft collar (to seal off air stripper gases, which works perfectly!) - had to do this because the Taipan barrel OD is larger than the Crown barrel sleeve

This brought me up to 65FPE (1074FPS with JSB Monster RDs). Turned the reg down from 158 to 147 for 968FPS, but I realized afterwards that I did not have the right hammer spring installed 😣 

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My gun will arrive early next week. Really looking forward to stepping up from a Marauder, not to say I haven't had fun with that gun. I haven't set up a regulator, is there a gauge on the gun that shows it's set pressure or is there a tool to buy to check before assembling the gun? Anything else fun I should know or play with besides lining up some ground squirrels? This has been a very informative thread. Thanks.