Moly destroyed some SMK's

I recently found a plastic tub with 100 Sierra 338 cal 250 gr Match Kings, covered fairly thickly with Moly and some 300 grain SMKs coated with Tungsten Disulfide, that had been put in a box and left there for many years unintentionally. I usually tumble them in dry corn cob before putting them on the shelf, but forgot to with this batch.

On the Moly coated ones, when found, I figured, GREAT, some more boolits to launch without having to spend money! Sadly, when I took a close look at them I could see that the moly had created serious pits all over most of the bullets. There were also big chunks of Moly on some bullets that were very difficult to scrape off using a knife. I washed them off in Dawn and tumbled until there was no Moly left and they now look like someone hit them with a torch. Every one was discolored and deformed with craters and pits all over them. Crud. The batch of 300 grain SMK's coated with Tungsten Disulfide that were in the same location as the Moly batch, also still heavily coated with the Tungsten dust. I feared that they too were also ruined, but after tumbling a bit, to remove the stuck on excess powder, they looked PERFECT.

I knew that Moly can etch / pit barrel steel which is why I quit using it to coat bullets 6+ years ago, and switched to Tungsten Disulfide(?), but I had no idea it could eat away at copper like that. I am going to use them for foulers most likely rather than giving them a proper burial. So, if any of you are still using Moly, don't leave the bullets in the powder too long or you might regret it.

The photo link below shows what they looked like. Top bullet is a Berger for comparison, middle is the 250 SMK destroyed by Moly, bottom is a 300 gr SMK that was handled virtually the same as the 250 but was coated with Tungsten.

http://imgur.com/yCPOKWm

http://imgur.com/yCPOKWm

Interesting.................

WOW, the moly really screwed up those bullets! :apologetic:

Moly by itself won't screw up anything. I've got bullets that were coated 20 yrs ago that are just fine.

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Originally Posted by sharpshooter

Moly by itself won't screw up anything. I've got bullets that were coated 20 yrs ago that are just fine.

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So do I, some are probably 30 years old, no problems, but it sure did make a mess of these. The only thing different between those that are in fine condition to the trashed batch is that they had quite a bit of moly dust still adhering to them and were stored that way for at least 5 years under the same conditions as the others.

I have never seen anything like this before.

The mystery continues.............

I think i read something somewhere about moly attracting moisture? and reacting causticaly with it?

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Originally Posted by granite1

I think i read something somewhere about moly attracting moisture? and reacting causticaly with it?

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Correct. It can etch barrel steel, which is why I stopped using it. I didn't know it would also do the same to copper.

By the way, I tumbled these with some ceramic beads and then coated with Titanium Nitride and 90% of them look quite good. I am going to try shooting a few with a known good load for this bullet. If they shoot well, the ones that have clearly visible pits in them will be saved for fouling shots and the other ones will be used up on steel at 1K.

geezerhood, what kind of benefits are you seeing with your tungsten disulfide coating?

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Originally Posted by 390fe

geezerhood, what kind of benefits are you seeing with your tungsten disulfide coating?

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I use it to extend the number of rounds I can shoot without cleaning. When I first started coating using Moly, I didn't notice an increase in accuracy for any particular barrel, but it didn't fall off as fast. Now, I work up all my loads from the get go with coated bullets, and have for many years.

I started using Moly in a 17 Rem that would not go more than 20 rounds, without a major cleaning. Bullets breaking up before they hit the target, keyholing etc. After reading about all the problems one MIGHT have with Moly, plus the fact that it rubs off too easily, I switched to Tungsten Disulfide. The Tungsten is very difficult to remove compared to the Moly. I think the correct chemical symbol is WS₂. With the Tungsten coating I can literally go 100+ rounds before accuracy becomes unacceptable for varmints with pretty much any of my fast centerfires like the 17 Rem, 204 Ruger, 22-250 AI, 6mm-284. One time on a P-Dog hunt I almost hit 150 rounds with a 204 ruger ER Shaw barell and it was still giving me 100% hits on P-Dogs. When I eventually cleaned it there was very little copper sign considering.

I also have used it with rougher factory barrels that coppered up rapidly, less then 15 shots. Again, it increased the number of rounds I could fire without heavy copper causing problems by 2-3 times.

Now, I pretty much use it with everything I shoot from 17 Rem to 50 BMG, since I have a system set up that makes coating them easy and I know it will give me more shooting time between cleaning.

Thanks for your reply, i appreciate it!

Welcome.

I just cleaned an X-Caliber 338 Lapua barrel the other day that had only Tungsten coated bullets shot in, about 120 rounds. It barely turned the patch blue.

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Originally Posted by geezerhood

I use it to extend the number of rounds I can shoot without cleaning. When I first started coating using Moly, I didn't notice an increase in accuracy for any particular barrel, but it didn't fall off as fast. Now, I work up all my loads from the get go with coated bullets, and have for many years.

I started using Moly in a 17 Rem that would not go more than 20 rounds, without a major cleaning. Bullets breaking up before they hit the target, keyholing etc. After reading about all the problems one MIGHT have with Moly, plus the fact that it rubs off too easily, I switched to Tungsten Disulfide. The Tungsten is very difficult to remove compared to the Moly. I think the correct chemical symbol is WS₂. With the Tungsten coating I can literally go 100+ rounds before accuracy becomes unacceptable for varmints with pretty much any of my fast center fires like the 17 Rem, 204 Ruger, 22-250 AI, 6mm-284. One time on a P-Dog hunt I almost hit 150 rounds with a 204 ruger ER Shaw barell and it was still giving me 100% hits on P-Dogs. When I eventually cleaned it there was very little copper sign considering.

I also have used it with rougher factory barrels that coppered up rapidly, less then 15 shots. Again, it increased the number of rounds I could fire without heavy copper causing problems by 2-3 times.

Now, I pretty much use it with everything I shoot from 17 Rem to 50 BMG, since I have a system set up that makes coating them easy and I know it will give me more shooting time between cleaning.

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What is your procedure for coating with WS2? I have a 22-250 barrel that coppers up really bad after firing 60 rounds through it requiring a days cleaning with Wipeout and/or Montana Extreme 50 BMG. The barrel has at least 400 total rounds through it to date.

I was curious if this happens to Winchester ammo that has the black lubalox coating on them as well?

Wait till you try hBN.

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Originally Posted by SNORTHRUP1

I was curious if this happens to Winchester ammo that has the black lubalox coating on them as well?

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I doubt it. The bullets that were etched / corroded by the presence of the moly had a very thick coating on them. There was still a fairly large quantity of loose moly dust still in the container Some bullets had areas where there were chunks almost 1/16th of an inch thick. I intended to tumble them in paper towels but totally forgot and they sat there for years, which apparently is why they ended up damaged.

None of my other moly coated bullets that were cleaned with paper towel chunks after coating have ever shown an indication of etching though one batch of 50 BMG Amax bullets did turn bright blue and purple in a rainbow pattern, but the metal was still smooth.

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Originally Posted by Scott Evans

Wait till you try hBN.

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I have heard good things about that....not sure if I will ever try it though since the tungsten is working fine and I have hundreds of bullets already coated.

In powder form moly and tungsten disulfide will be quite hygroscopic (absorbs water from the air). Sulfuric acid can be formed in minute amounts. Remove the excess fluff you'll be OK in the future.

hBN doesn't change POI the first few shots and makes cleaning even easier. Doesn't prevent a hard carbon ring in the throat but everything else it helps tremendously, plus there isn't an hBN build-up like moly or WS2 in the bore. hBN is also effective at elevated temps unlike MS2/WS2.