Unfastening the very tightly screwed PCP Cylinder

[nmondal]

Shooters,
I was wondering does it happen sometime?
The PCP Cylinder becomes tightly screwed into the Pistol?
So hard that it is neigh impossible to rotate and remove it?
It has happened 3/4 times to me - in all cases someone else opened it up for me.
It just happened now with me, so I was wondering what you guys do if it happens?
Does it happen sometime?

[kevinweiho]

What brand of pcp pistol do you have? Lack of proper lubrication will cause galling, check the male and female threads, clean if dirty and apply some lube. Do not overtighten the cylinder on the pistol.

[David M]

Sounds like galling, happens a lot with mixed materials, steel male thread and alloy tank etc.
If you have two tanks, does it happen with both ?
Lube may help, but it may have gone too far.

[nmondal]

Walther LP 500. Cylinders are also Walther. It is now attached to the pistol and.. I can not unfasten it.
Found this too:
viewtopic.php?t=53837

[Gwhite]

One issue is that if you screw the cylinders on tight when they are full, they tend to get even tighter when they are empty. The seal does NOT depend on how tight the cylinder is. Just tight enough to keep it from flopping around is good.

As for removing it, you may be able to get a small strap wrench around it. If the problem is that you can't get an adequate grip, powdered rosin will also help.

[brent375hh]

I don't know if your barrel comes off easy like a Steyr, but if it does, that might help your access.

[deadeyedick]

If you do lube it make sure to use silicon grease or your problems may include degraded o rings.

A piece of thin rubber counter matting often provides better grip and the cylinder removal is much easier.

[Rover]

Yeah, the older Walthers used to have a hex fitting on the end of the cylinder so you could put a wrench on it.

When I have a too tight cylinder, I put the grip between my knees and use both hands to loosen the cylinder. It always works.

Follow Gwhite's advice.

[McMadCow]

If you do lube it make sure to use silicon grease or your problems may include degraded o rings.

Are you sure about that? Last time I used that on threads it nearly ruined my gun. That's for o-rings only in my house.

I have an LP-500 and I lube the threads with automotive anti-seize. It's made specifically for lubricating threads between dissimilar metals.

[nmondal]

Yeah, the older Walthers used to have a hex fitting on the end of the cylinder so you could put a wrench on it.

When I have a too tight cylinder, I put the grip between my knees and use both hands to loosen the cylinder. It always works.

Follow Gwhite's advice.

On it, did it!
I mean wow! I just did that knee thing and it just worked!
Also https://www.targettalk.org/memberlist.p ... ile&u=2404
kindly sent me a message explaining what bad I did!
====
stephen_maly wrote:Fri Jul 09, 2021 8:14 am
Hi there,
Did you by chance put the cylinder on the gun immediately after it was filled? If so, the cylinder would be warm, and when it cools, it would have shrunk slightly and become tighter. If that was the case, gently warm the cylinder base (with warm hands), and then try to undo it. You only need to put the cylinder on the gun until it just stops, and no tighter.
Steve
Wow! I just did that! WOW! Because my cylinder is faulty and it loses out air post 150 bar - so I immediately put it!
Thank you! I never got the idea!
======

[brent375hh]

If you do lube it make sure to use silicon grease or your problems may include degraded o rings.

Are you sure about that? Last time I used that on threads it nearly ruined my gun. That's for o-rings only in my house.

I have an LP-500 and I lube the threads with automotive anti-seize. It's made specifically for lubricating threads between dissimilar metals.

I tried silicone grease, and it felt like putting scouring powder on my threads. I went back to Superlube with Teflon that Pilkington shipped with my gun, and my cylinder went back to coming off with one finger and a thumb. I don't know what silicone is good for, but cylinder threads is not on that list in my limited experience.

[thirdwheel]

Never put silicone grease or oil on metal to metal contact eg threaded cylinders unless you want to promote galling and the parts becoming seized together. For this joint MOISTEN the O ring with silicone oil and put a VERY small amount of mineral grease that contains graphite on the threads, it will blow most of it out on changing the cylinders but enough will remain and the graphite will bond onto the metal surface and act as a lubricant for a long long time.

[Gwhite]

I think the Super Lube with PTFE is silicone based. It's just that the PTFE prevents galling problems. The silicone makes it O-ring friendly as well. I've been using it on O-rings and cylinder threads for quite a while on dozens of pistols, and never had a problem.

[brent375hh]

Once a year I add a little moly powder to the SuperLube dab I put on my threads. It seems to help as well.

[thirdwheel]

For graphite read MOLY! It creates a physical bond the the surface of the metals.

[nmondal]

Can anyone pls give me some sort of Amazon link for the products in question?
I sort of got silicone grease which destroyed my earlier AP 20 Pro gun.
Hence, very cautious.
What I know definitely works is the Olive oil - that too if the gun gets jammed.
Not on the PCP threads.

I found the superlube here.
https://www.amazon.in/Super-Lube-51004- ... 000UKUHXK/
(I am in India)

[Gwhite]

You have to be careful. Super Lube makes all kinds of stuff, including silicone grease which you want to avoid for threads & metal to metal contact.

This is what I use, and is recommended and sold by our host, who knows a lot more about air gun maintenance than most:

https://www.amazon.in/Super-Lube-21010- ... B005R2NIIC

There was an old posting that Super Lube Silicone grease, even with added PTFE, is bad on cylinder threads:

viewtopic.php?t=63634&p=306395#p306302

The synthetic oil with PTFE is probably OK, but grease is generally better for most air gun applications. The Super Lube synthetic grease is compatible with the majority of common O-ring materials, including Nitrile, polyurethane, Viton, etc.

https://www.super-lube.com/Content/Imag ... (PTFE).pdf

[divingin]

If you do lube it make sure to use silicon grease or your problems may include degraded o rings.

A piece of thin rubber counter matting often provides better grip and the cylinder removal is much easier.

Most cylinders I've seen (which isn't all that many) have the sealing O-ring separate from the mounting threads. Lubing the threads will not affect the O-rings in any way, unless you're really sloppy with the lube.

[David M]

We seem to have gotten off track with grease and "O" rings.

Most pistol "O" rings used are either Nitrile 70, Nitrile 90 or Vitron (green) and these are not affected by the petroleum grease.
The big reason not to use petroleum based grease is the very high air pressure and possible detonation or dieseling.

https://www.allorings.com/o-ring-compatibility

[Gwhite]

The issues of detonation & dieseling should primarily be in spring air pistols, where the air is compressed rapidly. It's not clear to me that high pressure air like used in PCP pistols is necessarily a problem with petroleum lubes, but I've never dug into it to be certain.