vulcan .25 unstable velocity !!
Nice to be with you guys, and hope to learn more.
Three months ago, I got my .25 vulcan tactic.
I screwed the hammer spring adjuster a little bit in, and was shooting at 920 FPS.
everything was ok, but for the past two weeks I have noticed some changes. So, I checked the velocity.
Filled to 250 bars, the gun shoots at 910 FPS.
When it reached 170 bars, it dropped directly to 870 FPS.
and when it gets to 150 bars, it goes down to 840 FPS.
Refilled and done the same steps again, I will always get the same results.
Is it the regulator? shall I take it out and check the o-ring!!
What do you suggest!!
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Postimage.org is good
actually I did not delete it.
I received a message from Anthony266 ( site admin ) saying that the pics I uploaded contained some sort of a virus. So he had to delete them all.
I dont know how did that happen, might be the upload center I used to upload those pics !
Anyway, I will try to upload them again to a different site and hopefully it will be O.K
no worries, this is not Airgunnation.
:rofl:
i think he deleted it himself by using the x
he did not want to see us the fat permanent marker pen marks he used to mark the reg rotation/position. lucky boy
😛
or it played up again and…
:rofl:
Weird.
Upperlight’s entire post about accomplishing his regulator fix has gone missing.
Where you have your regulator set now appears to be about where the best shooting/accuracy has been shown to be for this gun. What you might want to try is shooting and backing off the HS until you start to get a decay in speed, then bump it back up just a bit so that you get that consistent 900 or so fps… That would seem to be the sweet spot for these Vulcans. If you can shoot 890-900 with hammer spring set at minimum for that speed, you will have about as good a balance of speed/accuracy/efficienccy (shots between charges) as you’ll get with this gun.
I too must add that this forum is just simply awesome! This has been a fantastic thread to just follow along with… I’ve learned quite a bit from it.
Thank you for posting and thanks the rest of you for the great technical feedback and experience!
Thank you guykuo.
Surely I wish long life for my gun.. maybe I will reduce the the regulator pressure a bit.
The previous setting of the regulator was (70.65 mm ) that was the total length of the regulator, and and I had it marked at that point.
HOOT.. actually I have not tested accuracy yet.
I will soon hopefully, and maybe I will reduce the speed.
Thank you hsnmz.. I got my gun on December 2016
Kris, Thanks a lot :8:
well done
:8:
Goos job done. You were lucky to get that result without a regulator tester. Yours regulator looks a bit different. Mine is a gen 4 Vulcan but there is no snap washer on its regulator. When did you buy this gun?
:hoot:
Master tuner Ernest Rowe has pointed out there is a delicate balance between the hammer spring tension (HST), the valve, and the regulator. Each must be in balance with the other. You have reached that magic point. Your gun will shoot no better than you have it set at this time.
Maximum accuracy/power is achieved somewhere between 850 fps to 925 fps…beyond this point the pellet enters a “trans-sonic speed” and will begin to encounter buffeting from the air shock wave it is creating, which will lead to poor accuracy. Might I suggest you keep your gun at no more than 900 fps for maximum velocity and accuracy. There is little to be gained beyond this point except a few foot pounds of energy…a very few and not worth the accuracy loss.
Nice work! The first time I took an air gun apart, I ended up using the dang thing as a tire jack handle! Not everyone can do what you just did. Now shoot that rascal….have some fun!
Hoot:
That is great news. So happy you have it working.
I think you are maxed out on the possible FPS for the gun’s air chamber size/pressure/valve/transfer port at 930 FPS. That is actually high for the gun and caliber you are using. Going tighter on the HST won’t increasing velocity any further because you already got the hammer velocity to the highest degree of air release from the valve. Once HST is up to that point, making it hit harder doesn’t increase FPS, but increases mechanical wear on the valve.
You are seeing it drop with even more HST because you are going past the max point and possibly causing the hammer or valve to rebound closed. The total air release is then lower. That is too hard a hit by the hammer. I would recommend off to 900 – 910 FPS, if you value your Vulcan’s life span.
BTW, how far did you screw the adjuster out from seated to set your initial 140 bar setting?
Again, congratulations. :8:
Good point about backing off the HST if the regulator pressure is dropped down a lot.
I really am enjoying my “model air plane” parts that have made it so much easier to cock my Vulcan. :biggrinn:
Yep Evgeny sent me the same airplane parts and I assembled them on my Vulcan air tank. It sure makes it easier to control the puffs of air I send out of the air tank! :biggrinn: :8:
when i work in the regulator area, i wear disposable gloves, i have high consumption of these.And use lint free cloths or lens cleaning paper/tissue.
you dont want any hair or any particulates there! Should be clinical clean.
i would avoid using too much silicon too, attracts dirt.
o ring sizes are in the manual. plus if that is a new reg maybe more than the paint what has changed so show us some pictures. I dont think you need to go all the way in, just do one full turn in and see what happens. cant remember but i think i really see way too many threads visible there.
if you drop the reg pressure a lot, make sure you back out the hammer spring tension so you dont smack the valve too much. is the firing valve/pin OK? you can push in the valve stem all the way in with finger and it comes back springy hee?
i looked at the https://www.youtube.com/watch?v=5LLSVFbmHcs and https://www.youtube.com/watch?v=2TO6XkmRQOA,
and indeed his reg is longer and shows less threads… so it is really guesswork things have changed evidently.
if you watch the second video, you will see that how he went from way too high to suddenly way too low output pressure, so it is quite a narrow window you have to fit in, good luck with that.
maybe there is a way of working this out also by filling the cylinder to different pressures and chronoing the gun, but it will take ages.
Maybe the man can send you a new reg pre adjusted ??
give it one turn in and see, if you are struggling get a reg tester, maybe you can share one or something in the US.
Yes, the wording….
I really am enjoying my “model air plane” parts that have made it so much easier to cock my Vulcan. :biggrinn:
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Thank you cricket
so here they are uploaded to Postimage.org
This is the mark I made previously( its not that fat :rofl: ), it was shooting 905 FPS.I think it was about 140 bars.Maybe the number of the remaining threads will help anyone if he wants to adjest his regulator.
later, I turned the adjuster a little out. Now she is shooting 930 FPS