Whatever Happened to Moly Coated Bullets? - Page 4
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  1. #31
    Site Contributor-Certified Marlin & Milsurp Rifle Nut Super Moderator
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    Quote Originally Posted by gunscrewguy View Post
    How about moly lube for cast bullets?

    AC
    I have read about people trying this. No clue what the results were... I bet a quick search on cast boolits would yield something.
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  2. #32
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    It's been tried. But no real advantage and a lot of unnecessary work.

    Cast bullets swage to bore diameter as soon as they enter the rifling. Lead is a dead metal, and it has no elastic spring back, so once it is squeezed down to bore diameter, there is very little shear resistance.

    Jacketed bullets are coated with gilding metal and remain tight all the way up the barrel. That's partly why they can be 0.003" smaller than cast, their elasticity keeps them firmly against the lands. Moly lube helps (at least in theory) lube the gilding metal and keeps the copper from abrading off.

    On the other hand, leading is thought to be from propellant gas leaking around the base of the cast bullet and taking lead with it. That lead is then deposited on the barrel. It's a different mechanism unrelated to friction.

    These photos may help. They show jacketed bullets, both coated with moly and uncoated, after passing through the same rifle barrel. The bullets were not fired, but were hydraulically driven, so as not to risk deformation by the target. The moly coated bullets are purported to show less deformation to the driving area, and smoothly impressed, rather than engraved rifling.

    79AFF2C5-7310-4762-A3FD-76EC47A7DB1E_1_105_c.jpegC8776013-4D34-44C3-91FE-30C4E573F991_1_105_c.jpegFB655959-CFAD-4C9E-AEC1-83AC53668355_1_105_c.jpegFD162241-FF44-4A4B-9720-9839BA2207FF_1_105_c.jpeg


    Copied from Precision Shooting, Moly-Coated Bullet Drop Mystery Solved, Dan Hackett, Jan 1997.

    The smoother profiles of the moly treated bullets were used as an illustration to explain several reported advantages (at that time) of moly coated bullet ballistics. Those advantages were reported to include improved accuracy, superior ballistic coefficient compared to the same bullet uncoated, faster downrange velocity, minimal copper barrel fouling, and longer barrel life. There may be one or two more that I cannot remember.

    Practically, these advantages are most useful to target shooter, bench rest shooters, and long range varmint shooters who drive their bullets faster than 3400 fps. Unless the rifle and the shooter are capable of shooting wee, small groups--say less than 0.5 inch at 100 yards--the shooter is not likely to notice an improvement in accuracy. Advantages to Marlin lever rifle shooters would be minimal. Again, moly coating is not useful for cast bullets.
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  3. #33
    Tenderfoot
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    A few years ago, I came across some information that moly powder was never 100% pure. There are always minute amounts of other minerals or compounds, such as sulfur, calcium, etc, in the moly powder. There was a concern that moisture interacting with those minerals and compounds causing oxidation when in contact with the steel barrel. A few folks found oxidation after removing layers of moly that had lined their barrels from shooting moly coated bullets. Later I spoke to a couple folks at the Sierra Bullet booth at a SHOT Show, about this issue with moly, oxidation and barrels. Those Sierra Bullet folks were of the same opinion, and that was the reason why Sierra, at least at that time, did not produce any bullets that were moly coated.
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  5. #34
    Tenderfoot
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    I tried moly coated bulets when I was developing a load for my .243 win back around 2009. I believe they were Nosler or Hornady factory pre-coated varmint type bullets. They shot ok but non-coated bullets of the same weight grouped better out of this particular rifle. Plus when you went to clean the barrel the cleaning patches would come out black for days and it just made a mess. I didn't particularly care for that so I did not pursue coated bullets after that. Decided it was just a fad/marketing ploy.
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  6. #35
    Sidewinder
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    Whatever Happened to Moly Coated Bullets?


    They are on my bench I just dried them , from my vibrator/polisher.

    I started using moly as a major ingredient in my lube recipe, for my Marlin444. It keeps my barrel SUPER SHINY CLEAN, even after hundreds of rounds of my cast lead boolits. Since using it , I have not had to scrub my barrel for lead, or copper! In the past decade plus, as a lube ingredient, with bees wax and avocado oil,... it has worked so good for me, I was inspired to buy a moly dedicated bolt gun.

    I agree with all the complaints on how messy it can be. But, it doesn't have to be messy. Measuring and adding, the appropriate amount (very little) of moly to a vibrator, and then adding hot water to a level just above the load of acetone cleaned bullets,... results in an EXTREMELY CLEAN PROCESS,... imo! After draining , washing and drying,.... the moly does NOT come off the bullet from handling. I can't imagine working with moly in a dry state,... must be miserable, indeed!!!

    As for a dark barrel,... I haven't gotten that with my dedicated stainless steel bolt gun. And, I wouldn't care if it did. I use moly to coat, deeply,... and would consider a darkened barrel as a plus!

    I haven't gotten into all the ballistic pros and cons,... not interested,... as I stated, I could not be more happy with my moly lube/cast boolits, and that says all I need to know.

    Other than taking the published advice to NOT SHOOT UNCOATED COPPER BULLETS in a moly coated barrel,... I like working with it, very much!
    Last edited by ranchhand; 03-27-2020 at 09:48 AM.
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  7. #36
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    I just found this article. The Moly Saga ? Why Moly-Coating Has Fallen from Favor « Daily Bulletin

    According to the author, molybdenum disulfide will "out gas" or decompose to the molybdenum and a sulfur compound under the hige heat of powder combustion. This can leave sulfur compounds in the bore unless promptly cleaned afterward. (Think of black powder products of combustion, without the carbon and the potassium compounds). These compounds attract humidity and can cause corrosion under the moly layer in the bore.

    But it doesn't seem to be a problem for everyone, and stainless barrels may be more resistant than chromoly steel. And there are described cleaning methods that do not remove the moly layer necessitating firing a number of rounds to "re-treat" the barrel.

    This is offered as a partial explanation of my original question.

    I will continue to use moly coated bullets in my 7x57 as I believe the moly helps reduce pressure in my top loads.
    Gareth Holland likes this.
    NRA Endowment Life Member, SASS, OGCA, NC Watermen United
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  8. #37
    Sidewinder
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    HIKayaker,... I also have read that warning, in the past. But, I could never find a time table, warning how quick, or, how slow it would take to effect the barrel.

    Have you read anything along that line?

    Personally, without ever reading how quick it could happen, I came to the conclusion it would not have any detrimental accuracy effect, before I retired a moly dedicated barrel.

    I do live in the southwest desert, with only a few weeks of monsoon,... and extreme dry weather, for the rest of the year,... so, I don't worry about it, too much.

  9. #38
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    So far, no problems with the stainless barrel on my 7x57mm. But I haven't bore scoped it...
    Gareth Holland likes this.
    NRA Endowment Life Member, SASS, OGCA, NC Watermen United
    “If liberty means anything at all, it means the right to tell people what they do not want to hear.” -- George Orwell
    "Corruptissima in republica plurimae leges."--Tacitus
    The more numerous the laws, the more corrupt the government.


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