Moly Coated Bullets Damage Barrels? According To This They Do

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"Among competitive shooters there was a huge shift toward coated bullets a few years back, but they’ve since fallen from favor for many. It wasn’t because they don’t perform well, because they do, but there are ancillary, and important, liabilities. Mostly: moly-coated bullets can corrode barrel steel, including stainless. Molybdenum disulfide outgases (outgas is the release of an occluded gas vapor that was part of the compound; a state change, pretty much) at temperatures lower than firing temperatures, and that creates a residue that, when mixed with water (moisture from condensation included, like what happens after firing), is pretty much sulfuric acid. Yikes. Right. If a moly-coated barrel is cleaned (correctly) each use, no problems. But one of the big draws is the potential to get literally hundreds of rounds, on zero, before the barrel needed cleaning. After a conventional cleaning (solvent and brush) it also takes time, which is rounds through the barrel, before zero will return."

Here is the whole article: http://www.mssblog.com/2017/02/17/re...oated-bullets/

I have shot maybe 30K of Moly bullets out of rifles with zero issues. Once Hexagonal Boron Nitride (HBN) came on the scene I mostly switched. The only reason I switched is HBN is white and less messy to apply. I still have about half of the 8,900 87grain 6mm V-max moly coated that I got a great deal on.

None of my fellow HP shooters had any of the claimed issues either.

http://bulletin.accurateshooter.com/tag/boron-nitride/

Well, it's on the internet so it must be true. I'll just throw all my stuff in the garbage

I watched the whole moly thing unfold pretty closely because I was interested in it.
I read some of the warnings and stuff then 20 years later I started using it.
the key is to get the moly laid down in a clean barrel then leave it there.
I now use moly as a main component in my boolit lubes, it generally is used in my 'better' [higher priced] guns.

I too have been using Moly (Neco-Coat Process) since the mid 1990's, even Moly some cast bullet rifle bullets..no problems so far. What advantage if any using HBN coating? would all Moly have to be removed from bore..if this is even possible after all this time? Maybe I should just stick with Moly?

The advantage to hBN is really the same as the concept behind moly. It reduces friction, supposedly helping with cold bore shots on target, and barrel life.

Anytime you reduce friction, you reduce pressure, and lose a bit of velocity. But, if you are already a moly user, you shouldn't see much change in that.

A lot of us have switched to HBN. I still know guys using moly, and I doubt they will ever stop.

Moly can cause some problems if you don't keep up with cleaning and maintaining your rifle. Some guys care, some guys don't.

HBN is great stuff. I find it more effective than moly. I use it on my long range jacketed competition ammo, and I mix it in to my super secret :) lube recipes. It really shines in lube IMO.

I have a box of moly coated 30cal bullets, loaded a few. But from what I read you either use moly or don't, cant go back and forth.

I have one gun that I shoot molly in, a 22-250 AI fast twist gun that I put a cam controlled scope on for several years, the cam was for a 50 BMG and the 75 SMK molly bullet matched the trajectory of the 50 exactly, at about 3,010 to 3,040 fps. I do not actually remember what weight bullet in the 50 matched the 75 as the scope is now long gone. It would not stay zeroed for very long in any case. But I still shoot the 75s in that custom 700 and still use it to shoot walking crows in a fresh disked field at 400-500 yards. I have never had a problem with the molly showing excessive wear either, but I never pushed it hard nor to excessive heat.
Ed

This corrosion warning seems to come up every so often..I have heard some lower grade Moly could contain excessive sulpher? In any case, I have only used the Moly powder purchased from NECO. One thing I do know, since 1995, the Moly impregnated steel balls have resided in a Thumlers tumbler plastic bowl in basement...during that time, Basement was damp & humid for lack of a non-icing de-humidifier during summer months. Humidity now is around 50% during hot summer months. If Moly was as corrosive as reported, I would expect those steel balls to be one solid mass of rust. Yesterday, I donned some rubber gloves & removed a spoonfull of those balls & rubbed them clean with an old worn out sock...nothing but bright rust-free steel. These balls will rust, as I found a couple I had dropped outside on patio that went thru a winter.

I've shot buckets of Moly coated bullets since the mid 90's with rather infrequent cleaning, and haven't had a single problem. Before using Moly, I'd spend more time cleaning copper fouling, than shooting groups. I've noticed with Moly coating, I don't get a lot of copper fouling.

Also, since the 90's, I've mixed the same NECO Moly, into whatever bullet lube I happen to be cooking-up with good results, as well as using Lyman Super Moly on cast bullets. Moly doesn't cause damage...

I was curious several years ago. I had some Moly powder from work. I tumbled it on FMJ target bullets. I had a high end AR barrel. I can't remember how many rounds or how long I was shooting but I had corrosion that I could clearly see on the lands and grooves at the end of the barrel. The only thing I did different was Moly coated bullets. It could be a coincidence. I don't use it anymore. It could have been the Moly I was using too.

My issue with moly is it coats the bore & accuracy suffers if you shoot non moly over that w/o a good cleaning. Just not worth the effort.

Been shooting moly in several rifles and handguns since '93, SS and CrMo barrels. My favorite rifle is my 7mm RM No.1. Nothing wrong with the bore at all. No signs of corrosion even though that rifle and myself have been soaked while hunting a few times. I clean it out and start fresh every few hundred rounds. I don't really have a rhyme or reason to, I just do. I really like not cleaning copper out of barrels.
My first experiments with moly were on commercial cast lead .44 boolits. First time I never experienced lead in the barrel. Now I keep it lead free with proper fitting boolits.

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Originally Posted by jonp

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After a conventional cleaning (solvent and brush) it also takes time, which is rounds through the barrel, before zero will return."

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And this--precoat the bore with Lyman Aerosol Moly, fire 2-3 shots and it'll be "broke-in" again.

I shot moly'd bullets (Neco) for I think 2 or 3 seasons in my match mule. Shot it twice a month and the bore was mopped out usually on the same day. I ended up with pitting in last 6" of the bore. None of the other rifles kept in the same room (seldom shot) were pitted. FWIW, the room was very humid--had a saltwater aquarium in it that burned off 1-2 gallons of water every day.

If you shoot moly, make sure you oil the bore ASAP after firing.