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Discussion Starter #1
So, I'm curious about the common wisdom about leaving gas systems dry vs oiled.

First we have the gas piston from a Steyr AUG as removed when the gas system wasn't lubricated between shooting sessions. Total of about 100 rounds fired over 3 shooting sessions.



This is the same gas piston after rubbing with a dry soft cloth. No solvent of any type was used to clean it.



Next is the gas piston after adding 1 drop of oil* to the gas piston after each shooting session. About 120 rounds fired in 3 shooting sessions. The piston wasn't removed to apply oil, I just did one drop on the face of the piston. The oil has crept over the entire surface of the gas piston and the whole thing is oily.



This is the same gas piston after rubbing with a dry soft cloth. No solvent of any type was used to clean it.



There wasn't appreciably more carbon on the piston after applying oil and then shooting it. What carbon there was was much easier to remove after it had the oil on it.

H

*Aeroshell Fluid 18
 

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I personally wipe down with a lube impregnated cloth and assemble and never have had a problem and clean up has normally been easy. So I would say "semi-dry" lol
 

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Regarding the m14/m1a, you're supposed to make the gas piston and cylinder as dry as possible before reassembly/use. I would be surprised if any other piston system didn't required the same. This area is where most of the carbon buildup occurs, and any moisture will attract the particles, and when they dry it would make a clump, add in the heat of operation and you could bake the carbon on, oil itself could bake onto the surfaces like it does on car parts, ever had oil leak onto heads or a header/exhaust manifold? All of this has me curious, Sadlak makes a titanium nitride coated piston for the m14/m1a, it literally only requires wipe-off with a cloth and it's clean, I wonder if any other companies make something similar for the newer piston rifles.

And while the carbon itself didn't exactly stick to the oil, it still builds up more where there's contact with fluid which can hinder the operation of the piston, and while carbon build up would take a while to do any real harm, dirt and sand in the air would be a different story.
 
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When I first read in the manual that you always run the piston dry, I wondered why and thought it could cause excessive ware . After thinking about this, I thought it may be for safety measures due to the fact that oil will explode under high pressers. I thought that maybe a dry lube, such as Hornady one shot might work well for this. But have never used it . Interesting results you had though .
 

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Dry, carbon is abrasive. You do not want to collect it, as it would with the oil. Yes it is easier to wipe off when wet.
 

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I can't remember what I did when I tore my FS2K apart & removed ( lube it or not upon re assembly ) I did follow the lubrication points in the manual, but I do recall that the Gas system was " carbon fouled " and took quite a while to clean up , there was so much debris in the piston area that I had to drive it out with a long brass rod. Wish I would have taken pics. After running the Scar suppressed for several months, I expect it to be even dirtier.

Hey " H " , thanks for your eval & testing, very interesting.
 

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Discussion Starter #8
Regarding the m14/m1a, you're supposed to make the gas piston and cylinder as dry as possible before reassembly/use. I would be surprised if any other piston system didn't required the same. This area is where most of the carbon buildup occurs, and any moisture will attract the particles, and when they dry it would make a clump, add in the heat of operation and you could bake the carbon on, oil itself could bake onto the surfaces like it does on car parts, ever had oil leak onto heads or a header/exhaust manifold? All of this has me curious, Sadlak makes a titanium nitride coated piston for the m14/m1a, it literally only requires wipe-off with a cloth and it's clean, I wonder if any other companies make something similar for the newer piston rifles.

And while the carbon itself didn't exactly stick to the oil, it still builds up more where there's contact with fluid which can hinder the operation of the piston, and while carbon build up would take a while to do any real harm, dirt and sand in the air would be a different story.
'Run it dry' has always been the received wisdom about gas systems. Reasons I've heard have varied from 'oil turns to carbon', 'oil will bake on and increase fouling', to 'oil in the gas system will detonate and explode'.

I was curious so I wanted to try dry vs oiled myself. If oiling is bad I wanted to have the most extreme test I could fit in with my normal routine of practicing before a match: shoot, oil, shoot, oil, shoot, oil and then clean. But even after applying oil repeatedely and not cleaning between shooting sessions the oiled gas piston was easier to clean than when dry.

I don't have a M1A, so I can't try that one. But I suspect that oiling the gas system there would work better also.

H
 
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