I read all the previous posts on Moly coated bullets, and my question is this: I got a ridiculous deal on some cartridges loaded with Speer 168 gr Moly coated bullets. Question: Will it affect my rifle if I shoot say, 5 boxes of them, than go back to copper jacketed bullets?
The first reason is that moly is prone to hydrate and the Disulphide in the Molybdenum Disulphide will become acidic. It's a weak acid but remember it is down in the pores and cracks where it can do the most damage. This is one reason why it has fallen from favor. Granted, I've only ever seen one instance first hand of moly corrosion. It was on a buddy's stainless R700 barrel with a muzzle brake. The moly had caked up in the gap between the brake and muzzle crown and once removed, the perfect 11deg crown looked like it was etched damascus with severe pitting. This was over the course of 4ish years and a couple thousand rounds. Fortunately, a re-crown saved it. After we did a follow up about how this happened, it was revealed that it was the moly, left in there for so long soaking up moisture. Had he bothered to remove the muzzle device and wipe it off once in a while it would not have happened. But you know hunters with custom rifles and beautifully blended machine work so you can't even tell where the barrel ends and the brake begins shudder at the thought of removing anything like that.
Secondly, moly is a PITA to keep up with. Once you go moly you can only shoot moly. Running naked bullets down a moly bore will eventually lead to a moly/ cooper build up that is akin to hard plating your bore with fouling. You cant even use copper bore brushes to clean with because copper residue from the brush will stick to whatever moly didn't get scraped off and leave you with an uneven bore, unless you completely remove the moly and start over each time you clean.
I went down this road and lost interest pretty quick when my groups didn't show results proportionate to the effort.
It is possible to safely shoot moly, If you are willing to keep up with it, but I no longer recommend its use. Latigo/zfk55 posted an excellent thread on using hbn coating.....and now I can't seem to find it. This hbn stuff is one of those things I really want to try for extending barrel life. finding a source for hbn is proving the hard part.
13fcolt:
That is good information. I was looking at recommendations on the Armalite site and they recommend moly ammo in
one of their technotes
. I have never used it and was almost going to buy some. Thanks for the warning.
It's a dry lube that does not cause a galvanic reaction like graphite can, does not hydrate and conducts heat very well making it useful for high temp 1000c applications. Getting it to stick to bullets is a bit more involved than moly but not much and you don't have worry about getting moly smears on your fingers and then everything else.
Thanks for the heads up JT, looks like I will be getting my hands on the stuff at last.
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