TargetTalk

I have been experiencing problems recently when screwing on or off the air cylinder on my LP400. It is extremely difficult to screw the cylinder all the way on when the air cylinder is full. The initial few screw threads are ok but it becomes extremely difficult to turn the cylinder once it mates with the air pistol and air is available to transfer from the cylinder to the gun. I am no longer able to fully tighten the cylinder by hand. (I have an XL grip so I'm no weakling !!) It only becomes possible to fully tighten the cylinder after a number of shots have been made and the pressure in the cylinder reduces. The cylinder is being filled from a 200 Bar scuba tank and the gauge on the cylinder reads no higher than 200 Bar when full. Has anybody had similar experiences ? Any advise as to what may have gone wrong ?

Rick

Hi Rick,

I would be contacting Chris from Frontier Arms in Adelaide and advising the problem. Being the importers, they would be your best bet to have the problem resolved.

If you come to the CMPC champs at SISC next wekend 20-21, you might see some fellow shooters with the LP400

Cheers
Brad

Thanks Brad. I just shot off an email to Frontier and will wait and see what happens.

I'm trying to get to SISC next week but it's three Sunday's shooting in a row for me. I'll be there if the ball & chain will let me out to play again ;-)

Rick

A little bit of lube goes a long way. (Silicone Dive tank grease)

Thanks Dave, I'll give that a try but I'm not sure it will help as when the cylinder is empty it screws on and off quite easily.

I suspect that somehow pressurised air is getting into the space between the cylinder recess and the threaded shaft that the cylinder screws onto. As a result of this highly pressurised air the cylinder is being forced away from the gun but can't move because it is partially threaded onto the shaft. As I continue to screw the cylinder on, the empty space between cylinder and gun thread reduces thus increasing the pressure and force/friction applied by the cylinder against the thread. The force increases to such an extent that I can no longer turn the cylinder by hand and thus cannot completely screw the cylinder onto the gun

David M



Joined: 24 Mar 2004
Posts: 511

Posted: Thu Apr 11, 2013 10:22 pm Post subject:
A little bit of lube goes a long way. (Silicone Dive tank grease)



This is the correct approach. You should need nothing more than a dab of silicone grease.

I think you may possibly have a problem, perhaps not, to save messing about I'd get your time zones right and phone the German factory service guys direct, everyone speaks perfect English, 0049 7 31 1539 0 ,ask for the service dept, you will get the correct guidance in minutes.

For lube I recommend a synthetic oil/grease, not a silicone based lube. Silicone is great for rubber seals or plastic parts, but in my opinion it is inadequate for metal to metal and might cause premature wear. I recommend a synthetic oil/grease because if some gets on any rubber o rings, they will not be effected.

Ok, I put some dive grease on the thread and tried again without success.

If anything it's getting worse. I also noticed that it is getting harder to thread the cylinder onto the fill adapter as well which would seem to indicate that maybe it's a cylinder problem. I hope so - it should be easy to fix by swapping out.

The photo below shows the size of the gap. I can't tighten it beyond this without using two hands or some tools which I don't want to do. Even with two hands I can't completely close the gap.

Just a thought:
Your problem seems to start at the moment the system comes under pressure. So maybe the cylinder valve opens to early and should be adjusted? Then you'll only have increased resistance for maybe the last turn of the thread.

On my MG1E it's about 1/2 turn from where the valve opens with a slight "click" till the cylinder is firmly seated.

Having the same problem with mine....I'm leaning towards a synthetic lube on the threads solution....silicone grease did not work for me either.

On my LP400 I use a thin smear of coppercote type grease used by machine shops for lubricating the screws that clamp the carbide inserts in toolholders. Mine is an early model and I felt the threads begin to pickup which usually precedes a good amount of galling. I keep the grease clear of any oring or seal - just on the engaging threads.

Does the gun function with the cylinder screwed in until tight?

The problem is caused by galling between the steel tank fitting and the alloy attachment on the frame.
It is caused by lack of lubrication on the threads, unfortunately once the threads have galled it is very difficult to repair the surface. Best way is to replace the alloy mount and use lube.

From Wikipedia...
"Galling is a form of wear caused by adhesion between sliding surfaces. When a material galls, some of it is pulled with the contacting surface, especially if there is a large amount of force compressing the surfaces together. Galling is caused by a combination of friction and adhesion between the surfaces, followed by slipping and tearing of crystal structure beneath the surface. This will generally leave some material stuck or even friction welded to the adjacent surface, while the galled material may appear gouged with balled-up or torn lumps of material stuck to its surface.
Galling is most commonly found in metal surfaces that are in sliding contact with each other. It is especially common where there is inadequate lubrication between the surfaces. However, certain metals will generally be more prone to galling, due to the atomic stucture of their crystals. For example, aluminum is a metal which will gall very easily, whereas annealed (softened) steel is slightly more resistant to galling. Steel that is fully hardened is very resistant to galling."

I have said before to use silicone dive tank grease, with years of use I have never had any problems with it.

"Pure Silicone Grease lubricates and conditions your valuable equipment.

This product is ideal for use on:
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Aquaseal Brand Silicone Grease is specially formulated to permeate rubber surfaces to provide deep, long lasting conditioning
Treated products resist drying and cracking and provide a better seal
Also great to waterproof flashlights, medical equipment, electrical connectors, pipe fittings and anywhere resistance to moisture and degradation is desired
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Permeates the surface of materials for thorough lubrication
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There has been a near missed accident involving one of these LP400 cylinders that has been used extensively. The cylinder was propelling away from the LP400 while it was screwed onto the LP400. The aluminum thread on the cylinder was stripped off. It looked like a spring.

So it is better to get it replaced.

I'd be interested to see some photos of the threads on the cylinder and mount of rloebler's pistol if possible.

What kbc wrote, happened to two cases in my country. Both lp400 were quite new

Why not use a tiny dab of anti-seize? So far, my cylinder hasn't had any problems.

Joel

You should put a small amount of grease on the threads of the regulator. It will transfer to the female threads on the cylinder. When screwing in the cylinder, if you meet any resistance, unscrew it and start again. Do not force it or you will damage the threads on the cylinder. Put a little grease on the threads of the air filling adapter also. After filling the cylinder, it is sometimes difficult to unscrew the cylinder from the adapter. Whenever it starts to get tight again, add a little more grease.



The gunsmiths recommend Super Lube® Grease, which you can get from www.pilkguns.com or a hardware store.