RELOADERS CORNER: What Happened To Moly-Coated Bullets?

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All the rage in 1998 and all but dead 2018: here’s a look at some reasons why. KEEP READING

moly coated bullets

Glen Zediker

In a way, I guess nothing really happened to molybdenum-disulfide-coated bullets (“moly-coated”). They’re still for sale, as are means to make up your own. What I mean is why didn’t they attain the sustained popularity they started with about 20 years ago, back when many forecasted they would virtually replace bare bullets? Here’s my take, from my experience, on “what happened.”

I don’t know any shooter who tried them and wasn’t excited about results. I sho was!

Performance-wise, moly has a lot of benefits. A lot. The first and most: take two bullets, one coated and one bare, put the same load behind them, then shoot and chronograph. The coated bullet goes slower. How is that a help? The reason it goes slower is because moly drops chamber pressure (into and through the bore easier). And! That velocity loss (at least 50 fps, usually more) is not, proportionately, nearly as much as the accompanying drop in pressure (usually ballpark 4000+ psi). (These figures vary with the cartridge, but all show similar universal influence.) So. The moly-load can be increased beyond previous “maximum” velocity: the idea is to take the coated load up to normal chamber pressure. It works! It’s common to need at the least 1+ grain more propellant to level the coated load with the original bare-bullet load.

Other advantages: Most see improved velocity consistency, evidently resulting from the coating alone. The coated bullets seem to have no limit to the number of rounds that can be fired with no change in accuracy or impact location. Of course there is a limit, but I knew many going beyond 500 rounds between cleanings. And when I say “many,” I’m talking about serious competitive shooters. Another benefit is increased barrel life (less rapid throat erosion), and this is, I think, due to a faster-accelerating bullet getting into and through the throat more quickly (less intense flame). Moly bullets also release sooner from the case neck (additional “tension” is recommended).

I “switched.” (The motivation to write this came from a weekend shop-cleaning where I restacked a huge many boxes of coated bullets, and wondered if I’d ever shoot them…)

I got more bullet speed and zero loss of zero: big benefits to an NRA High Power Service Rifle shooter. 88 rounds per day, and 80gr bullets through a 20-inch barrel trying their best to get to 600 yards in close proximity of one another.

moly barrel cleaning
Here was my solution to cleaning up after moly: Kroil penetrating oil and abrasive-type bore paste. This combination got it gone, and zero didn’t leave in the process.

What is bad, then, about moly-coated bullets? Moly itself! It coats the bore with a layer of residue. This layer traps moisture and will, not can, corrode the steel underneath it.  More: molybdenum disulfide outgases (outgas is the release of an occluded gas vapor that was part of the compound; a state change, pretty much) at lower than firing temperatures. That creates a chemical that, when mixed with water (including post-firing condensation), becomes, pretty much, sulfuric acid. That meant that the whole “zillion rounds between cleanings” didn’t really work. I know many who “lost” barrels, expensive barrels.

If the barrel is cleaned (correctly) after each use, no problems. But then another advantage is lost because starting with a clean barrel it takes quite a few rounds to return to zero. The layer has to be recreated.

The residue is x-difficult to remove. It doesn’t respond to routine means for bore maintenance, mostly meaning brush-and-solvent. The only way I found to get it gone was using micro-penetrating oil in conjunction with an abrasive paste-type cleaner, such as USP Bore Paste or JB Bore Compound.

bn coated bullets
Boron Nitride (BN) is an alternative that functions, in my experience, the same but with fewer drawbacks. One is that it’s “clear,” not as messy. Bullet on the left is coated. Still, though, I think that shooting coated bullets is an “all or nothing” proposition. Good groups are not likely to come “mixing” bare and coated bullets through the same barrel.

I no longer use coated bullets. There are other coatings that have fewer disadvantages, like boron-nitride (doesn’t outgas), and some of the proprietary baked-on coatings a few major makers (like Barnes and Winchester) use don’t exhibit the post-firing issues “conventional” moly-coating creates (which usually was moly powder, followed by wax, which added to the tenacity of the residue).

However, another issue is that accuracy tends to suffer running bare bullets though a residue-coated bore (which results after only a few coated rounds, that are coated with anything). All that means, in short, is that running coated bullets is something that really has to be bought into. It’s a commitment, as I see it, and, as with many such things, pushing the limits on performance requires more attention to detail, more effort. It’s a matter of value.

lyman moly kit
Here’s an easy way to get bullets coated: Lyman’s Super Moly Kit. Just add a tumbler. The two bowls contain the media, moly, and bullets and then go into a vibratory-type tumbler. The 6 ounces worth of moly powder will coat thousands of bullets. It works well.

Weigh the pros and cons. I honestly cannot, and will not, tell anyone not to use them. Coating can provide a serious performance increase. I don’t use moly-coat anymore, but that’s because my shooting needs are not so “serious” as they once were. I, yes, have gotten a tad amount lazy. I want to go to the range and enjoy my rifles and not lose sleep over the possibility of creeping corrosion if I didn’t clean up. I also want to be able to shoot different loads, including factory ammo, and maintain accuracy.

Last words: IF you choose moly, take steps to protect the barrel bore against the potential for damage. At the least, run some petroleum-based oil through the bore after shooting if you can’t clean it soon.

Tell about your experiences with moly.

See what Midsouth offers HERE

This article is adapted from Glen’s books, Handloading For Competition and Top-Grade Ammo, available at Midsouth HERE. For more information about other books by Glen, visit ZedikerPublishing.com

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19 thoughts on “RELOADERS CORNER: What Happened To Moly-Coated Bullets?”

  1. What about powder coating lead pistol bullets instead of conventional lubes?
    Any problems with corrosion or clean up? I have shot some and the bores look clean in a S&W 66 and 69.

    1. I don’t seem to recall anyone complaining about any residue left behind in a barrel due to PC. As a matter of fact, most find that it seems to polish the bore., as you’ve also seen I don’t know if that “polish” translates into faster wear or not, nobody has complained about that either.

  2. Glenn: Have you ever used Ballistol Oil for cleaning and defeating corrosion. Created in the early 1900’s for the Vehrmacht, German chemists created a unique oil that defies all the rules of oils as we know them. Like, Ballistol amalgamates with water. The properties are so special and unique that you need to look up this product and see for yourself it’s unique properties. I use it on and in all of my guns and in my home in ways that you would never use a normal oil. Please let me know what you find – I bet that you could use this oil to penetrate and remove the “Moly” with normal cleaning procedures while protecting the metal from harm. I use it on wood stocks without any hesitation with great results. This oil does NOT congeal – ever!! It has such a low “self adhesion” level that it is a great penetrating solvent able to traverse the smallest openings and work it’s magic.

  3. Thanks for this article. Wasn’t aware of these drawbacks; though I never got into shooting moly bullets because of perceived “messiness”. I have the same question as jp.

  4. I was one of the original Moly guys. When first experimenting with it, 3 tumblers were used and it was a messy process. The serious guys were cleaning their barrels anyway and many were using solutions like Sweet’s or Champion’s Choice so the cleaning issue wasn’t an issue. The same users then ran a wet mop of Moly Bore Prep down their barrels, let it sit for a bit and then ran a dry patch down it. I still Moly my bullets & barrel to this day and enjoy the same accuracy I had back when it was all the rage. The Moly part is dirty and I hate that part. Shooting a one hole group, worth it. Nice Article, thanks

  5. I have been using moly starting 1968 in a 244 Remington custom with a Douglas barrel no problems over 5000 rounds . Used a moly powder dry coated just enough to chance color to light gray. I also pulled a wet patch of Hopps’s through after shooting and dry patches no brushes then a damp patch with silicone spray still have rifle no corrosion .

  6. The best thin that I found out about moly coated bullets is that WalMart carburetor cleaner will remove the majority of it from my large batch of Combined Technology .308 150 gr bullets.

  7. When moly first appeared on the shooting scene I didn’t hesitate. From my day job, I already knew about moly’s superior crush strength and lubricating qualities on heavily loaded sliding wear surfaces. Just what a bullet needs! I’ve been moly coating bullets ever since. Also, the addition of a very light coating of Carnauba wax enhances those qualities.

    In addition to reduced fouling and wear, chamber pressure is reduced 3-5%; significant for those shooting the 5.56 at NATO.

    Three things:
    1) Remove ALL excess moly on the coated bullets.
    2) Swab a CLEAN bore with a 40/60 solution of moly and SC#7, then IMMEDIATELY fire a coated bullet to ‘condition’ the bore.
    3) Within 24 hours or less after the shooting is done, clean the bore regardless of how many or how few rounds, or it will rust.

    1. Nothing like applying what you just said to a 80NMJHP & scoring a 10 or a X at a 1000m. I think author might regret putting Moly in “has been” category. I know many top shooters still using it. Good comment!

  8. I recently converted to using the wet method of moly coating bullets. Much less messy and always great results. Just use a Harbor Freight rock polisher instead of a vibratory cleaner. I don’t know if the water used in the process negates the effect of moisture on residue in the barrel, but it won’t get any better than in the coating process.

  9. I too jumped on the moly wagon in the late 90’s. Shooting 75-80 grainers through a Kreiger 1 in 7.75 26 “ ar space gun. I initially raised the powder charge to get the desired velocity and cleaned as usual. Several thousand rounds later I checked the throat with a Stoney point and found that I could not load long enough to get up on the rifling. I blamed this on moly and after a rebarrel it was no more moly for me. After reading this article now I wonder if my improper cleaning was to blame. Funny thing is that kreiger with the worn out throat would still shoot very good but I blamed it for not making high master. Two barrels later no high master.

  10. Tried Hornady 55 gr. molycoated in my 22 CHeata years ago. Every one keyholed @ 100 yards. Rifle would shoot a raged hole @ 100 yards with uncoated Hornady. Never shot any again.

    1. You needed to check your velocity and up powder to obtain what was needed to stabilize bullet .
      I have been using moly on 220 swift much better barrel life.
      No factory coated bullets coated myself on high quality bullets.

  11. my experience with an 8oz can of kroil. it all leaked out around the crimp at the bottom of the can. I complained to kano labs. eileen james response “they only sell direct, not to stocking dealers , and it’s designed to creep and thats what it did, would I like another can for $9.95 ?”
    How professional is that ! ?

    1. Well….that’s not great. Did you ask if they deliberately chose a container design which they KNEW would leak the contents, so that customers might be induced to buy more (in which case the consumer fraud agency of your state might be interested), or was it a manufacturing defect of a particular can, in which case they should supply you with a non-defective replacement product under some theory of general warranty of fitness…?

      (I’m not a lawyer; this is not legal advice) This is just a question.

      I will say that I’ve had a can of Kroil for half a decade, and it hasn’t noticeably leaked, so my thought would be that it was just a problem with the particular can you bought. Perhaps it was damaged in shipping, handling, or storage post-production, which really wouldn’t be in the control of Kano Labs, manufacturer of Kroil.

      1. I purchased it at a hardware store (a retail outlet that according to Eileen James shouldn’t have it ), used a little and it set on the back of my bench for a year or so . It looks in good shape ,never dropped etc. Her response seemed snotty, like I was BS’ing her. No offer of compensation was made, just to sell me another (leaky can ?)I did mention the fire hazard it creates . I still have the can (in a plastic bag) .
        I wrote a letter to Kano explaining it all—no response .

  12. Mr. Zediker, You sure brought a smile to my face with this topic. Like some of the others, I’ve been using Moly for a very long time. Been trying to remember how long and apparently I’m too old to restore that memory.

    I first heard about it in Precision Shooting magazine where they ran (maybe) a 3-series article. Seem to remember Norma was running some kind of “Life Test” on a barrel with a hot 6.5mm of some sort. I had a barrel with a high number of kills through it and really dreaded the day I’d have to replace it. So I decided to try Moly in it to see if I could somehow extend it’s effective usefulness. It is still killing wide open. It is certainly not a benchrest rifle and was never intended to be, but will average in the 6s when my old eyes do their part. That kills as far out as I want to.

    I was raised to clean a shot barrel before you went to bed, and occasionally when it has not been shot. Always put a very light coat of moly grease down the barrel after cleaning and finished with a dry patch. I’ve not seen the rust problem some mention. I have enough Moly to outlast me and will continue to shoot it in all my rifles.

    Yes, it is a bit messy to apply to the bullets and some good old “Kit Carnuba Wax” (auto polish) for 10sec in corn cob, puts a heck of a finish on them.

    Nice topic. Best of luck to all you Moly users.

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