Home AR-15 Ar barrel thread Grease

Ar barrel thread Grease

By
sam sevdalis
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1193
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update to grease showing texture and color differences between ar15 barrel nut and upper thread grease

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10 COMMENTS

  1. Petroleum based lubricants contain solvents that continue to evaporate into asphalt. Synthetic lubricant does not evaporate. I have used Lucas Red 100% Synthetic High Speed/hi temp wheel bearing grease for years. I use Anti Seize (the grey stuff) on barrel nuts.

  5. Wrong! Synthetics, be it oil or grease are different at the chain link levels. Synthetics are vastly superior to petroleum based lubes. Synthetics do not vaporize as easily, flow better at lower temps, on and on. There is more to synthetics than just the additive package put in the lube!

  6. Smells, consistency, color, transparency… NONE OF THAT MATTERS. That barrel thread is NOT really a load bearing or frictional surface — it'll bear about 60 ft-lbs that's about it and ANYTHING can deal with that including peanut butter.

    There are only THREE things which matter as far as barrel thread grease goes:-

    (1) It should not corrode Aluminum. Generally, this means you stay away from Lithium greases, some of which can increase galvanic corrosion of Aluminum alloys due to their (frequently fluorinated) formulations. You should also avoid stuff with copper powder because Copper + Aluminum in the presence of water — especially salt water — forms a battery.

    (2) It should be high temperature stable because the area around the chamber can get oil smoking hot. Gas blocks can see about 800 deg F. The barrel fail at 1400~1500 deg F.

    (3) It should contain an anti-seize agent. That is what you are putting the grease on for; you are NOT using the grease on the barrel nut for lubrication! That barrel nut shouldn't be moving in use.

    OK, there are many options out there.The best I think is Dow Corning's Molykote P-37 Ultrapure High-Temp paste. This retains its anti-seize properties from -20 to 2,550 deg F. It is designed specifically for aluminum-aluminum joints, is totally non-corrosive and 100% metal free. The problem is that they don't sell this shit in a small tube or jar. You can buy BIG can for $40~$50 but that is more than you'll ever use unless you are planning on building 1000 AR-15s.

    The El Cheapo option that works well is Loctite Silver Anti-Seize paste. Loctite Silver grade is good up to 1,600 deg F (your barrel will fail before it cooks). It does contain metallic powders but not copper so there's nothing to corrode aluminum in the long run. And, you can get this in a tiny 1Oz tube for $2~3, so that's nice!

  8. There is a lot in choosing the grease in assembling the upper for the AR. I am no expert but I did look into it a bit. The product that the military wants is Molybdenum disulfide.
    The Molybdenum disulfide helps protect the threads from steel to aluminum corrosion in the event (rare event) that the coating fails. BUT that is a rare event, some people do not use grease and have good rifles so it all comes down to what you want.

    The most interesting thing there is is the "mill spec" choice Aeroshell. Mill Spec is pretty much "most bang for your buck." In other words there are better products for this application out there but the most difficult thing is finding them, and for a consumer and not a producer, the prices for retail and wholesale can be different, And consistency from batch to batch.
    Therefore my first choice would be Aeroshell, and my second choice would be a Molybdenum disulfide grease.

    In reality any bearing grease can do as long as it does not contain copper and/or Graphite.

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