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Tuning Doux Technologies Plenum Upgrade for Air Venturi Avenger
- Thread starter SkeeterHawk
- Start date
Anyone notice that after installing the Doux plenum you have to set your reg higher for it to not creep?
I had mine set at 1,400-1500 psi to shoot CPHP and it would creep to 1,800 or 2k after sitting overnight. No big deal, I dry fire 5 and then it goes to where it's set. Mind you this is after sanding the delrin on the end of the reg flat on glass with 3000 grit paper.
Well now I decided to see what some JSB 18.13 would do through mine and I knew I'd have to up the reg for these heavies, so I put it at 1.6k and I didn't notice as much of creep maybe up to 1.8k overnight after filling my bottle to 4k.
Also, I just shot the most consistent shot string of 10 I've ever done with these results:
847, 845.6, 846.8, 846.8, 847.9, 847.9, 845.6, 846.8, 849.1, 845.6
If you do the math (or use a std dev calculator like me lol) you'd see my Std Dev is just 1.093 ! I do have the AE Swede 2nd reg set to 2.8k but still this is amazing to me, a PCP novice.
Anyway, just wondering if having a large plenum would affect the stock reg creep from being set low in the range since most of the time people get these to shoot heavies or slugs without cranking everything up.
Thanks!
I had mine set at 1,400-1500 psi to shoot CPHP and it would creep to 1,800 or 2k after sitting overnight. No big deal, I dry fire 5 and then it goes to where it's set. Mind you this is after sanding the delrin on the end of the reg flat on glass with 3000 grit paper.
Well now I decided to see what some JSB 18.13 would do through mine and I knew I'd have to up the reg for these heavies, so I put it at 1.6k and I didn't notice as much of creep maybe up to 1.8k overnight after filling my bottle to 4k.
Also, I just shot the most consistent shot string of 10 I've ever done with these results:
847, 845.6, 846.8, 846.8, 847.9, 847.9, 845.6, 846.8, 849.1, 845.6
If you do the math (or use a std dev calculator like me lol) you'd see my Std Dev is just 1.093 ! I do have the AE Swede 2nd reg set to 2.8k but still this is amazing to me, a PCP novice.
Anyway, just wondering if having a large plenum would affect the stock reg creep from being set low in the range since most of the time people get these to shoot heavies or slugs without cranking everything up.
Thanks!
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If you take out your stock poppet spring you can take it to hardware store and compare them easily. Unless they have metric sizes you will end up with a 3/8 diameter spring. The tricky part is picking the length and wire diameter that works best. The stock spring is very stiff. You can put a really light one in there.
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Aea you'll still be working on your gun and itll still have the stock mediocre performance.
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Well I finally decided to add a power plenum to my Avenger so I made one today at the shop. I'm not sure on the volume of it but it works good. I have the regulator set at 2800psi and the hammer is tensioned about halfway and I'm getting 825fps with 40grain slugs and 955fps with 27 grain pellets. Not bad for a .25 caliber but I hate the way these look with a plenum. It's just goofy looking to me. And im fully aware that my welds have some low spots but I machined a deep groove in both pieces before tig welding it so it has good weld penetration. 
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Nice work!
The guy that built mine put a small piece of carbon fiber over it to neaten it up.
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Anyone know why a .22 Avenger would not be able to push a 25.39 JSB more than 800 fps with a 20CC external plenum? I could do 930 fps with a 18.13 JSB with the Doux 11 cc at 2.2k reg and 3.5HS and thought the 20cc would let me shoot the 25.39 just as fast.
Tried all regulator settings like 2.2 to 2.6k for the 20cc all at max HS and highest I got was 800 fps.
Tried all regulator settings like 2.2 to 2.6k for the 20cc all at max HS and highest I got was 800 fps.
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I have found the same thing with mine. I get about 38FPE max, so that is why I shoot the 21.14gr Baracuda. That allows me to get up to the 900FPS range. I am thinking to get the power up further, I would have to mess with the transfer port, valve, etc. I'm pretty happy with the performance with the Baracuda, so I haven't messed with it that far. The barrel tolerates slugs, but doesn't really like them, so I am sticking with pellets.
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Bummer... was really hoping to use these 25.39 gr. to get more than the 35 fpe I could get out of my Doux plenum and the 18.13s.
I ordered these springs : https://www.ebay.com/itm/185812002783
But probably will only do the hammer spring cause I really don't want to fully disassemble this thing to get to the valve spring.
You think it will be safe to use that heavier hammer spring with no other changes?
I like those Baracuda 21.14 a lot I just haven't found a place to get them in bulk and my go to place Trenier doesn't sell H & N. So I tried heavier JSB instead
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The 25.39 JSB spiral like a corkscrew out of my Avenger, but Baracuda 21.14 travel straight. Dont know why.
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Yeah I just shot a bunch of the FX 5.52mm 25.39 gr this weekend. With the 20cc plenum and the heavy hammer spring installed , at 2.6k psi and 3 HS I was able to get 50 fpe (940s)
The spring from ebay is very strong. At 2.1k psi and HS backed out, it shot 840 fps which was max fps I got with the stock spring all the way in at same reg psi for 25.39gr.
At the 2.6k psi it also made my Avenger loud so I'm trying to see if I can get good fps #'s from lower reg psi but higher HS and find the ~97% knee.
The 25.39 is very heavy for .22. I think that's why it needs more fps to shoot well, besides i think JSB version is 5.5 where the FX is 5.52mm. I did not shoot paper but at spinners at 75 yards. I'll have to hit paper when I figure out what reg and HS settings I end up with to see if I can get these shooting as well as the 18.13gr I had used all up til now.
Accuracy is everything so if the 25.39 really don't work out (quiet it down w/tune) then I'll pull the 21.14 H&N out to test those. They're very good quality I just like JSB / FX because I buy from Trenier who unfortunately doesn't have H&N.
The spring from ebay is very strong. At 2.1k psi and HS backed out, it shot 840 fps which was max fps I got with the stock spring all the way in at same reg psi for 25.39gr.
At the 2.6k psi it also made my Avenger loud so I'm trying to see if I can get good fps #'s from lower reg psi but higher HS and find the ~97% knee.
The 25.39 is very heavy for .22. I think that's why it needs more fps to shoot well, besides i think JSB version is 5.5 where the FX is 5.52mm. I did not shoot paper but at spinners at 75 yards. I'll have to hit paper when I figure out what reg and HS settings I end up with to see if I can get these shooting as well as the 18.13gr I had used all up til now.
Accuracy is everything so if the 25.39 really don't work out (quiet it down w/tune) then I'll pull the 21.14 H&N out to test those. They're very good quality I just like JSB / FX because I buy from Trenier who unfortunately doesn't have H&N.
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That was great information @EmptyTin_Tim !! I figured that the HS would make a big difference, but I didn't expect it to be THAT much!
Just wondering, when you are saying that you are shooting 25.39gr JSB or FX...I assume that you are talking about the JSB Monster Redesigned, correct? I wonder if the regular JSB Monster will shoot with your velocity up like that? For me, they spiraled like crazy. I was off by 2' in just 50 yards.
Another question, since you have your power up now, do you have any of the same weight JSB knock out slugs? I don't get good accuracy with those either, but my power is lower. Unfortunately, I don't have a solid barrel cleaning rod (I use a patch worm), so I don't know my exact twist rate. I suspect that it is in the neighborhood of the 1:26 or 1:30 others have measured as this thing LOVES pellets, but tolerates slugs. It really only shoots the FX Hybrid decent.
Anyway, I'd be interested to know your thoughts.
Jonathan
Just wondering, when you are saying that you are shooting 25.39gr JSB or FX...I assume that you are talking about the JSB Monster Redesigned, correct? I wonder if the regular JSB Monster will shoot with your velocity up like that? For me, they spiraled like crazy. I was off by 2' in just 50 yards.
Another question, since you have your power up now, do you have any of the same weight JSB knock out slugs? I don't get good accuracy with those either, but my power is lower. Unfortunately, I don't have a solid barrel cleaning rod (I use a patch worm), so I don't know my exact twist rate. I suspect that it is in the neighborhood of the 1:26 or 1:30 others have measured as this thing LOVES pellets, but tolerates slugs. It really only shoots the FX Hybrid decent.
Anyway, I'd be interested to know your thoughts.
Jonathan
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I am shooting these
And yes this spring is a huge difference. It is very strong and was nice it came in red powder coat and I got the light valve spring too but didn't install that.
It gets good #'s and speed just is so loud at that power. I've tried going again starting lower reg and seeing if that's it but the spring is so powerful you need to be in the 2.4k range for it to start balancing. It had a trend of being top speed at 1HS or 2HS at those lower pressures like 1.8k - 2.0k psi
Weirdly, at each reg setting the 0 HS all had about 805 fps or so. You'd think it'd go up or down but I tried 1.8, 2.0, 2.2, 2.4 and they all were about that.
1.8k 25.39 gr
0HS 800,
1HS 811
2 HS 832
3 HS 828, 822
4 HS 832
2k 25.39
0 HS 802,
1 HS 830, 833, 833,
2 HS 848, 835
3 HS 850 loud, 850
2.2k 25.39
0HS 816
1 HS 843, 842, 845,
2HS 860, 860, 868
3HS 873, 870
2.4k 25.39
0 HS 806
1HS 853, 845, 850,
2HS 870, 873
3HS 892, 890, 893, 890, 897, 898
I ran out of air after that was gonna do 2.6k again which is about where I pushed to 940 fps. That's NOT total shot taken I just would randomly start jotting down #'s after messing with setting that's why some have one fps others have a short string.
So for slugs all I have is NSA 17.5gr in .216, .2165, .217 and 20.2 in .216 and .217 I don't have any others although have heard FX is good but $$ per shot.
I think this likes the FX since they're 5.52mm not 5.5 although I'm sure that with the weight is why they are hard to push to >940 fps even with the spring. I mean it can do it its just you use so much air and also it is LOUD.
I think I may attempt a different tune with the OEM spring again just because that's how I got my accuracy with the 18.13gr JSB at ~930 fps but it was way quieter. I mean I wanna try to find similar but with OEM spring and 25.39 gr. Idk if possible but the guy who sells the spring on Ebay said Avenger OEM spring has trouble pushing open the valve around 2.4k psi which is where his heavy spring starts to shine in terms of fps gains.
I'm not sure of rotation but yeah mine likes pellets a lot too. I have done the full barrel polish to mine with that compound and mop but didn't measure when it was apart.
I still need to punch paper with these 25.39 gr but they seem decent and not tumbling when hitting my spinner at 75 yards.
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Update:
I shoot in my backyard and the new spring and higher psi just make this too loud. Those #'s were impressive but I can't justify the noise. I went back to my 18.13 gr around 935 fps. In curiosity I shot the 25.39 at the same tune of 2.4k with about 5 HS and wow those things spiraled like crazy. Just for kicks I tried the 25.39 out of my Notos which was just hilarious to watch them do a loop de loop downrange.
You'd definitely need to be pushing the 25.39 very quickly to get any stability out of an Avenger barrel.
I was looking around because I was curious if anyone had luck with the 25.39 in an Avenger and found https://www.airgunnation.com/threads/my-22-avenger-build.1304328/
He had all sorts of work done to his Avenger, more than mine. I can't believe that wouldn't sound like a 12 ga. I've noticed the higher psi gets you more noise even if you are at the 97% I tune my Avenger at 2 or 2.2k normally for the 935 fps 18.13 and it was never that loud at those psi as it was higher up even with stock HS but I think if the barrel were longer then the Avenger would love the tune I was going for. That spring is just so strong 0HS is like 5 HS on the oem spring.
Anyway, yeah 25.39 spiral and I gave up on the strong spring cause I couldn't get it quiet enough to justify the #'s, especially cause I could get way more shots/fill at a lower tune.
I shoot in my backyard and the new spring and higher psi just make this too loud. Those #'s were impressive but I can't justify the noise. I went back to my 18.13 gr around 935 fps. In curiosity I shot the 25.39 at the same tune of 2.4k with about 5 HS and wow those things spiraled like crazy. Just for kicks I tried the 25.39 out of my Notos which was just hilarious to watch them do a loop de loop downrange.
You'd definitely need to be pushing the 25.39 very quickly to get any stability out of an Avenger barrel.
I was looking around because I was curious if anyone had luck with the 25.39 in an Avenger and found https://www.airgunnation.com/threads/my-22-avenger-build.1304328/
He had all sorts of work done to his Avenger, more than mine. I can't believe that wouldn't sound like a 12 ga. I've noticed the higher psi gets you more noise even if you are at the 97% I tune my Avenger at 2 or 2.2k normally for the 935 fps 18.13 and it was never that loud at those psi as it was higher up even with stock HS but I think if the barrel were longer then the Avenger would love the tune I was going for. That spring is just so strong 0HS is like 5 HS on the oem spring.
Anyway, yeah 25.39 spiral and I gave up on the strong spring cause I couldn't get it quiet enough to justify the #'s, especially cause I could get way more shots/fill at a lower tune.
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