Airgun Technologies Vulcan 3 HP .25 max fpe?

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Will74

Will74

Member
Jan 27, 2019
124
90
Uusimaa, Finland
Let's get into it from this perspective. Some of you know I have been having trouble extracting oomph out of my Vulcan 3 HP in .25cal and I wrote many detailed posts about it.
I can get about 115fpe and from what I can gather, there was more at first. A lot more.

Anyone?

No tuning tips please. If you can be bothered to read my related posts then it's another story.

Max fpe!

Thanks
 
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Is it possible that the hammer spring has taken a set and is not hitting the valve as hard? From my reading the new V3 has a conventional valve vs. The balanced valve from the V2. That could explain the loss in FPE. I should add, that’s still a lot of power from a .25 cal. I’d be pretty happy with it from just the output and conventional valve.
 
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Hobbyman2007 said:
Is it possible that the hammer spring has taken a set and is not hitting the valve as hard? From my reading the new V3 has a conventional valve vs. The balanced valve from the V2. That could explain the loss in FPE. I should add, that’s still a lot of power from a .25 cal. I’d be pretty happy with it from just the output and conventional valve.
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I hear you but apparently hammer spring is not related.
The problem is that the performance is erratic, however impressive.
Thanks for input.
 
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JaceSpace1369 said:
Could be the fact that you have the depinger in there. It takes up space, not a whole lot, but it takes up space. When I put the depinger on my V3 .30 500mm my fps dropped from 880fps to 830fps
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Naah.
There used to be way more power. Didn't touch s**t, and suddenly those readings were a faraway dream. So it ain't the depinger.
 
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Buck_Wild said:
Will74, out of curiosity which chronograph are you using?
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Readings are meters per second obviously, me living in Europe that is.
Zan 51,8gr slugs (.253)

IMG_20240916_134903.jpg
 
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Buck_Wild said:
I have a crony F1 and I get very inaccurate readings if there’s too much sunlight outside or not enough light altogether. Personally, I would try to set up indoors with controlled lighting, much more accurate and consistent.
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Thanks, but it has always been consistent enough. Trustworthy.
It has served well for some ten thousand pellets / slugs and seems to be going strong. The only trouble it has given me is under sunlight, and it only leads to Error, or not reading at all. I have never had reason to question it. My P15 still shoots within 2fps through it but it has Huma reg in it. Nothing erratic about that.
It's the V3 that's bugging the crap out of me.

Thanks
 
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My cheap $25 chinese chronograph that mounts to my barrel doesn’t require a light source and is reading within 2 fps of the f1 chrony when the light source is fixed above the diffusers. When I was strictly using the F1 chrony I experimented with moving the overhead lights around and it did affect my readings. Just my experience. I hope you get it figured out soon!

Is the gun shooting accurately and consistently even with lower than previous chrony numbers? At what distance are you testing accuracy?
 
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Buck_Wild said:
My cheap $25 chinese chronograph that mounts to my barrel doesn’t require a light source and is reading within 2 fps of the f1 chrony when the light source is fixed above the diffusers. When I was strictly using the F1 chrony I experimented with moving the overhead lights around and it did affect my readings. Just my experience. I hope you get it figured out soon!

Is the gun shooting accurately and consistently even with lower than previous chrony numbers? At what distance are you testing accuracy?
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No, the gun is not shooting accurately, at least not up to my standards. The distance has been around 100 yards which has been convenient down on the dairy farm.
I haven't put much effort into accuracy since I know there's something wrong with the gun.
The chrony reads fine every week and tuning surely has an effect. It's just that power is amiss.
Although I don't necessarily need it all, this is not how I roll and then there's the erraticness.
 
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This is what I check when I have inconsistent values . Chrony, then hammer spring , then regulator pressure. If those check out. I move onto leaks from transfer ports, around barrel, breech seal and probe . If those check out it’s time to move to a deep clean of the action. I’ve seen all kinds of debris and gummy substances inside my guns. I don’t use any oils in my actions as I find temperatures will affect hammer strikes with changing temps.
 
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JaceSpace1369 said:
You never know. Sometimes we rack our brains, so damn hard that we miss things that are pretty simple.

Did you ever change factory spring to the stronger spring? I have the stronger spring at home so I can measure it if you want to compare sizes. What is your reg set to?
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Yeah it all started when I tried to use the AAO spring. I never even cocked the gun with it because it was so damn heavy and made the horrible scraping sound.
I immediately put the original back on and there it was. The power never came back except maybe once, and I'll tell you more about it later.

I have no reason to suspect reg setting having originally been anything but the advertized 200bar.
I have tried as high as 220 but the (original) hammer spring couldn't handle it. I believe I'm at 205 to 210 at the moment. Could well go lower depending on the slug of choice but I need to find the culprit first.

So there was this one time I saw those old numbers on the chrony. It seems to have been a reg malfunction giving just the right (wrong) pressure for those few shots.
I'm not much for knee but of course the hammer spring is always set lower than the reg.

I'm forced to determine reg setting from combination of fill system and the bottle gauge. The Wika helps.

IMG_20241020_163513.jpg
 
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