BEST piston head o-ring lubrication for DMR airseal

Discussion in 'Gun Building, Modifications & Repairs' started by Adman234, Jul 31, 2012.

  1. 100% silicone (what I use now)

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  2. Silicone gear grease (what I used for RS SVD)

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  3. Silicone grease (thick silicone oil)

    100.0%
  4. Superlube

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  5. Griffing's super-secret **** (lube)

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  6. Other (PLEASE post below)

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  1. Adman234

    Adman234 Active Member

    3,022
    9
    Wildwood
    DO NOT POST/VOTE IF YOU ARE STUPID OR DON'T KNOW WHAT YOU ARE TALKING ABOUT. I DO NOT WANT TO KNOW ABOUT YOUR FRIEND WHO BUILT A SUPER-LEET SNIPER RIFLE, I WANT TO KNOW ABOUT YOUR BUILD! When you vote, PLEASE post an explanation or info.

    OK, so here's the issue. I finished my DMR gearbox, and having not even assembled the gun yet, I can tell that there is an airseal issue because the air output from the GB is not even as high as my RPK.

    I am running a full stroke M190 with double bearings.

    My air-seal components are SOLID.

    -Guarder clone PHEAD
    -Home depot stretched heated #14 o-ring
    -Chromed stock cylinder
    -Gasketed lonex cylinder head
    -SHS aluminum nozzle with o-ring
    -M190 style reaps bucking
    -Metal hopup unit

    I can do a full airseal test, pressing the piston as hard as I can, and there is no leak. It is sealed great with 100% silicone.

    But when I dry-fire the gearbox, the air strength is very very low. Not enough to move a piston body more than a few inches along the ground.

    All my other air-seal components are literally worryproof, the nozzle seals perfectly on the cylinder head, the cylinder head has double orings AND permatex. So the issue, it seems, like any other DMR build, is the piston head o-ring.

    So what works for you? For my RS SVD, I used silicone gear grease and it worked better then 100% silicone oil, so I'm thinking I should use that. Please give me your knowledgeable opinion.
     
    Last edited: Jul 31, 2012
  2. Mystery43_4

    Mystery43_4 New Member

    1,307
    2
    Santa Barbara
    For DMR's I use a heavier weight silicone oil. While my current oil (bought off Evike a couple of years ago intended for propane adaptors) isn't labeled by weight, think of pancake syrup consistency. That and I stretch the Oring a little more than on ROF builds. For a DMR, I stretch it to where it is just enough friction to where if you hold the Cylinder vertical and try and drop the Piston into the Cyl, it won't drop freely. Don't stretch it too much past that point though, otherwise you'll be wearing down Orings.

    For my ROF builds, I stretch or sand it to where the piston is easily able to drop into the Cylinder, but will still make an air tight seal when need be. This helps avoid PE for the ROF set ups, but for Semi Auto DMR's it's alright to have a little more friction.

    The light weight oil I use is a SuperLube product. It comes in a little clear plastic tube with needle applicator. I'd imagine it's around a 15 weight. I use this for piston rails, and sometimes for the Cyl. I've actually started using the same heavier weight oil for most builds, and it's holding up fine.
     

  3. Adman234

    Adman234 Active Member

    3,022
    9
    Wildwood
    Hmm, there is tons of friction in my piston head oring, I stretch much more than that. It usually requires a bit of force to slide it.

    I will try the heavier silicone grease (GHK) that I have. It is just about like pancake syrup, so it might be perfect.
     
  4. Lefse

    Lefse Well-Known Member Supporting Member

    6,226
    1,837
    I use pure silicone grease when lubing my cylinders and o-rings. Before I just used regular silicone spray, the silicone grease works much better, gives perfect airseal in the cylinder with minimal friction.
     
  5. RCV

    RCV New Member

    2,852
    1
    Even though I voted for Griffin's homemade lube, I have always used a more viscous grease. Permatex dielectric to be exact. It never wears out and it is a really fine grease for minimal friction. It can be found at Autozone.
     
  6. ThompsonFTW

    ThompsonFTW New Member

    3,062
    0
    Dayton
    Voted other. I use the same thing as RCV uses. (He got it from me. ;)) The lube is really thick but seals amazingly. Also as RCV said it never wears out. I use it to seal the cylinder head as well.
     
  7. CoppertopNeasg

    CoppertopNeasg New Member

    1,440
    2
    Boston
    I agree with nortech I also use silicon grease in all of my builds. It lasts the longest and seal the best in my opinion.
     
    Last edited: Aug 1, 2012