Vulcan REGULATOR Remove & Replace

Do not try this at home or abroad as working with high pressure air is dangerous ❗
BUT ther are videos and instructions on the internet that may not be complete enough so I decided to learn as I proceed from instructions provided by “kris” and his and others help.
It is difficult to do this all in one post so bear with me.

This procedure works for me on my Vulcan 5.5/22. Different versions of the Regulator and rifle parts have been noted by others so these instructions may not apply to your particular Vulcan.

If you don’t know where you are coming from you won’t know what direction you need to go.
“guykuo” did a good explanation of how to determine the set point or “knee” from any of 3 different types of velocity graphs.
http://talonairgun.com/forum/viewtopic.php?f=54&t=33609&p=343761&hilit=Knee#p343761

Here is my Vulcan Regulator so you know what you may expect to find:

The following work should be done in a CLEAN WORK AREA free from dust, breezes, and anything that might contaminate the greasy parts that are removed and the interior of the air tank. “kris” suggests wearing gloves to prevent contamination fron body hair. That’s how important it is ❗
Assuming you use good tools of the proper sizes I’ll skip the Tools List. But here is what my home made cloths hanger hook looks like. Notice that I cut it part way up the side for the ready made 90° angled hook portion. The end should be filed and sanded smooth to prevent damaging the interior of the tank:

STEPS

1) Remove all ammo, DeCock and place Safety ON, remove Scope and any other attachments.

2) Begin Slowly DeGassing the Air Tank. While it is DeGassing continue to next step.

3) Remove Shroud.

4) When Tank pressure is Zero, remove the DeGassing Grub Screw and the Tiny Ball Bearing (Note, a magnet may help get the Ball out and prevent it from playing hide-n-seek on the floor)

PAUSE
+Before Step 5 is a good time to closely examine the Quick Fill Cover as to its free movement by turning AND ITS PLAY PULLING AND PUSHING IT. There should be a gap between the Cover and the Tank. Also examine how the holes line up with each other. If you later screw this in to far the holes may not align and inserting the Fill Probe may damage its o-rings.

5) Insert the Fill Probe into the Quick Fill Hole. It is Not a Torsion Bar. It only needs to marry the Quick Fill Body to the Quick Fill Cover so you can use the pretty knurled end to unscrew them from the EMPTY Air Tank.

6) Using the Hook. Look in side the tank for the round brass adjusting screw in the middle of the shinny silver 17mm locking nut. You can gently probe the sides of the brass part for a hole that goes all the way through it. Sorta like fishing. If the moon is in the right place you should have 2 chances to hook
one.

IF REMOVAL OF YOUR AIR TANK IS NECESSARY SKIP ON TO VERSION V 1.01 “Air Tank Removal”. Then return here to proceed with Step 7.

CONTINUED

STEPS 7-15

7) Assuming you took the bleeder grub screw all the way out and captured the tiny ball bearing with a magnet, there should be no vacuum pulling the REG back in when you let up pulling. Anyway, it may be hard to get it started to move but when it does, slow down. When the REG o-rings get to the threaded area, go real slow an maybe wiggle the REG slightly as you work the o-rings over the threads. Note; the REG may have a good amount of lube on it. Don’t let it get dirty ❗
+++ 💡 I strongly recommend “kris'” Bleeder Hole O-Ring addition for everyone ❗ Without it you are likely to have trouble sealing the Bleeder Hole and have a non-detectable over night leak. Like “kris” said the o-ring will relieve a lot of stress from the threads.

8) NO, you can’t adjust the REG now ❗ ❗ You MUST Measure it and record the measurement. I’ve heard of one at 72mm and although mine was set high it only measured 71mm. Go figure ❗ in fact walk away and relax. When relaxed come back and measure it again. When you have two consecutive identical relaxed measurements you may proceed at your own risk.

9) NO, you can’t adjust the REG yet ❗ ❗ with a felt marking pin, mark the end of the brass adjuster so next time you will see where to insert the wire hook to pull the REG out.
ALSO mark in line with the hook hole on just one side of the black REG body below the locking nut with a pencil. No, not on the silver nut because it will lock down in a different position after the adjuster screw is turned.

10) Ready, set, adjust. Or on second thought, what was your REG set at just prior to opening it up. Is your plan to increase the set point or decrease it ❓
For my big change of about 35 BAR, I believe I ended up with only 0,67mm decrease in length of the REG. I 1st went 1/2 turn from 71mm to 70mm and got lost in space. Back 1/4 turn and still way to low. Backed out a little further to about 70.67mm and that put mine at about 110 BAR. Your mileage may be a lot different. It’s trial and re-adjust but if you measure correctly you should be able to get it back to where it was.

11) Re-Assemble;
If you put the REG in backwards and gas it up I wonder if it will ever open up again. Ya know, I don’t know if the tank can go together backwards either. Mine had 5 dots on the front end where my vented shroud blows lead dust out. From the muzzle end put the Chamber tube in first followed by the big flat end of the REG. Your brass adjusting screw will be where you can see it again as before. Ease the Reg past the threads and use the clean rod to shove it to the other end.

12) install the Quick Fill Body and Cover. It will get tighter as the the o-ring engages the tank wall. DO NOT SCREW THE QUICK FILL BODY TIGHT ❗ ❗
Snug it loosely and back it out some so that the Quick Fill Cover Is free to turn. Pull the Fill Probe and check that the Fill Probe cover hole can be centered over the Fill Probe Hole in the Quick Fill Body. If this part is to far in, it could cause problems with the Fill Probe O-Rings. Don’t worry if it is loose and still able to turn as air pressure will tighten it.

13) Install the Bleeder Hole Ball Bearing.and Grub Screw. I would hold off on installing “kris'” o-ring mod until you are sure you won’t have to pull the REG again. Your choice. It is hard to get a seal without it but it is hard to get out otherwise. I won’t say how I got it out one time but it did take a while to find all 3 parts.

14) Fill er up Just Enough to run a short string. If it ain’t right, you won’t waste as much air.

15) Yes you can do this adjustment without a test gauge but it may take 3 or more attempts to get it right.

16) REPEAT STEPS 1-15 Until Desired Results Are Obtained. It only took me 3 times to get desirea le results. It was very easy to do the 3rd time and who knows if I shoot up my 18.13 gr. Ammo maybe I’ll fine tune it again for 15.9 gr. or some really heavy slugs ❓

COUTINUED WITH “Air Tank R & R” in this same thread.
Please someone sell us a test gauge setup for our Vulcans ❗

“Air Tank R & R”

First do STEPS 1-7 of “Vulcan REGULATOR Remove & Replace”.

After this section “Air Tank R & R” is complete return to “Vulcan REGULATOR Remove & Replace” and complete STEPS 7-16.

STEPS

1) Remove the Bolt Handle and the 8 Coulisse Cover side Plate Screws. ( Good time to consider reversing the mechanism for a right handed cocking bolt. )

2) Loosen and remove 4 Tank Clamping Screws. Not listed in the manual but you’ll see them inside the side plates. They are silver. They are supposed to be tight but after DeGassing mine were not all tight. No need to remove your nuts but make sure you don’t loose them.

3) Make sure the Tank is clean especially at the Clamps. By hand you can unscrew the Air Tank. The Collar with the Bleeder Hole DOES NOT COME WITH IT. Careful, DO NOT Push the Tank sideways in any direction as you SLOWLY unscrew it and move it out. It could get scratched by the Clamps. Especially after it comes loose from the threads be extra careful to ease it all the out past the Clamps. As the Tank moves away from the threads the Chamber Tube will be loose to fall out and run away. It’s big but rolls really fast.

4) with the Air Tank removed you can use a clean piece of PVC pipe or other clean Non-Abrasive Rot to push the REG out. It closer to the back end but may be easier to work its o-rings past the threads to the front where you can get ahold of it and wiggle it over the threads.
5) Re-Install the Air Tank tube back through the Clamps and Screw it into the Collar. You know by now to be careful.
NOTE: A few very important things to keep in mind;
A) DO NOT INSTALL THE CLAMP SCREWS UNTIL THE TANK IS PRESSURIZED TO AT LEAST 180 BAR.
B) THEN WHEN YOU DO, Snug the outer 2 first, then proceed to gradually tighten them like you would a scope ring.
C) Not Now but before you slide the adjusted REG in you must first slide the Chamber Tube in.
D) Now return to “Vulcan REGULATOR Remove & Replace” and complete STEPS 7-16.