Vulcan 3 Long .30. ... Problem with regulator ... fixed !!!!!

[Emu]

I do not know what is happening with my Vulcan 3 Oong .30 Cal.

It arrived shooting the JSB´s 50.1 grain at around 1000 fps.

After filling the rifle to 3500 psi, the rifle strated shooting those pellets at 580 fps.

I have assambled and dissasambles the rifle many times, lubricated de internal and external o´rings of the regulator.

I have changed the possition of the regulator form forward (large plenum) to rear (small plenum) and again back to forward possition.

I have changed the intermal part of the regulator for the one of another the regulator of another Airgun Technology Vulcan 2 rifle (not the adjunting part). I have reassambled with all parts of the original regulator.

The definitve and inexplicable (for me) results are:

- After tunning the regulator, if the rifle if filled at 2500 psi, it shots the JSB´s 50.1 grain consistently at 970 fps. and gives many shots, maybe 35 or 40 shots.

- Above 2500 psi the rifle decrease power (2600 psi - 890 fps----- 3500 psi- 580 fps).

This rifle should be able to work perfectly if filled at 300 bar but only works well if filled at half of that preasure: at +- 140 bar.

Could someone figure out what is happening and what could be wrong?

I will appreciate your advice.

 

[bamavet55]

Have you checked the hammer spring tension?

When the velocity of my V3 dropped I found the hammer adjustment had backed out. I turned it in an applied a thread lock. No problem since then.

 

[Dairyboy]

There should be a set screw to hold the HS adjuster in place. Could have backed out. However based on what your saying it sounds like your reg isn't working anymore.

 

[Motorhead]

YUP ... regulator issue.

A drop in power as you state is a text book case of VALVE LOCK created by more pressure within plenum that the available hammer strike can no longer overcome to get poppet to open fully. Regulator is suffering BY-PASS that in such as case as yours where reg works great at lower pressure but not higher can be attributed to a single o-ring.



That o-ring is the one that seals the pressure / seat height adjustment thimble to the main regulator housing. ( NOT SPOOL O-rings ) When this o-ring goes bad, HP can flow around the seat to the LP side and this I'm 99% confident in being where your problem lies.



Scott S

 

[Emu]

I have played with the tensión spring of the hammer and I have confirmed is dully fixed. 

The high preassure o'ring of the regulator look ok. But as Scott point out, I will try changing that o'ring.

A new process of full disassamble begin (one more time). 

 

[Emu]

Back from having breakfast ouside with the wife and from mass. 

Already changed the o'rings of high preassure of the regulator. Rifle is re-filling Now.

Let's hope the advice of Scott be as accurate as the logic it has and that the new o'rings work as it ought to.

If the o'rings changed do not work, the result should be exactly the previos one above described: o'ring of low preassure working well and the one of high preassure not working at all.

Results should be ready in half an hour.

 

[Emu]

Filled the rifle to 160 bar and worked perfectly. 

Then filled the rifle to 250 bar and did not work again. 

Already order es a Huma Regulator. Eventually the Huma will arrive and I will share the results with the Huma. 

 

[Ranchibi]

Bummer...but glad you can still shoot it at a lower reg point before the Huma arrives.

 

[Peashooter]

I had the same happen to me yesterday, so i shot my V3 down to 110 - 120 bars, shooting 13 grainers about 900 FPS, then i filled the gun to 300 BAR and BAM ! the gun was only shooting 6-700 FPS.

But i just went for the hammer spring to get the juice up, shot strings spread and ST dev remained as they have always been



BTW as i am only shooting .177 here, damn i lot of shots on a fill, i have a hard time imagining someone would shoot the gun down and feel that was fast, or if say out pesting rats still have rats left to shoot when the bottle pressure get down around 110 BAR

 

[Emu]

I watched a video in YouTube of how the regulator works.

I am of the idea that the problem was in the number of lanes. Too many lanes were not allowing the piston to travel enough to seal the incoming of air.

I removed 4 lanes and reassembled the regulator and the rifle again.

Rife is now filling again.

I will share results.

 

[Emu]

Did not worked either !!!

 

[Emu]

Here it is how I solved the problem:

I made measures of total length of the regulator considering unscrew adjustments first at 150 bar and then to 200 bar untill I got with 64 mm an acceptable measure at both pressures (911 fps with JSB' 50.1 grain and 250 bar).

Then the adequate total length of the regulator, including the turns, was 64 mm.

So, taking into consideration my inexperience, lack of equipment, age and condition, I am considering this an absolute success.

With those 92 foot pounds the rifle is very usefull and the pellet should fly with stability, so I am done !!!

I had to send back the regulator to the rear position because in the front position (large plenum), during the long process, I notice that the external O'ring's with the pressure suffered small damage twice and I had to replace them. That should not be normal.

It is very difficult to tune a regulator without adequate equipment to see at what pressure it is regulating.