Way Off Topic--Moly-Coated J-Words.

[CZ93X62]

OK--I have now "inherited" over 1000 moly-coated bullets in 22 centerfire caliber. I never paid attention to moly-coating back when it was all the rage, I was interested in redcoats or castings--The End. What purpose does/did moly-coating serve? Does it set up a deposit in a rifle bore that causes problems for redcoats or castings? Trying to decide whether these gray dull things should stay and get shot or sent down the road. Help me out a bit, if you don't mind.

 

[Spindrift]

I have no personal experience with moly-coated, jacketed bullets. The Norma factory have performed extensive tests, where they found longer barrel life with moly-coated bullets.

Some people claim that you should clean the moly from the barrel before shooting regular jacketed bullets, because the residual moly will reduce accuracy. This excact topic is discussed in a norwegian forum. A long-range/F-class competitive shooter (who wears out like 4 target barrels a year) reported no ill effects when switching between moly and regular Jx during the same shooting session.

I would shoot them, with no worries.

 

[Matt]

I went deep into moly coating when it was the hot thing to do. Still have the “scientific” grade moly,
pure carnuba powdered wax, and the super hard
stainless steel shot to impact plate the moly onto the jacketed bullets. I’ve sold the RCBS sidewinders and extra drums needed to perform this miracle in increased accuracy, velocity, bore life, and ease of cleaning. After about 3 years I came to the conclusion that moly coating did nothing to help or hurt anything. No measurable accuracy or velocity increase (or decrease) in a lot of chronograph and accuracy testing in .223/5.56, .220 Swift, .308, and .300 Winchester Magnum.

1800 to 2000 rounds in the .300 causes accuracy to fall off noticeably and this was the same with or without moly coating.

The .308 I’m still shooting (getting close to 6,000 rounds) is a Sako with a factory heavy barrel. Sako barrels reportedly are “soft” but I don’t believe it. I shoot lead and jacketed back and forth with no special cleaning. Ed’s Red on a brush for a couple of strokes, a couple of wet patches, a couple of dry and ready to shoot. Was doing this when shooting moly and saw no extra bore buildup or change.

I did try some Sierra 168 Matchking factory moly coated to see if I was doing something wrong.
Nope. No advantage or disadvantage noted.

All this leads to me advising you to shoot them and treat them like any other jacketed bullet.

I recently found a box of moly coated of Sierra .224 69gr Matchkings from the old days. I’ll load them for my .224 Valkyrie with no special considerations or concerns.

 

[RicinYakima]

Yep, all a bunch of hype to sell a product. p.s. PhD ballistics expert Harold Vaughn said that MdS simple retarded the powder burn rate, so you had to had to add more to get pressure/velocity up to jacketed bullet speed.

 

[Bruce Drake]

shoot them but ensure you don't let the moly residue get damp or wet from water as it turns acidic in the bore. clean with a good oil after shooting and you should be fine.

 

[Gary]

I bought a bunch off a fella on another forum and I am in the process of removing the Moly with Acetone. Seems to work pretty good.

 

[Matt]

All my research indicates that molybdenum disulfide is not soluble in water and generally inert.

 

[david s]

Kroil oil has a good reputation for cleaning Moly. Moly bullets will leave a bore moly coated and this had a reputation for attracting moister (aka hygroscopic). By all means shoot and enjoy them just be aware of it's reputation.

 

[CZ93X62]

Awright, gents. I very much appreciate this information.

 

[fiver]

try rolling them in your wet tumbler with the normal citric acid solution if you want the coating off.
I done it in a regular tumbler with some BB's and it got like 90% off.

to shoot them just work up your load from a clean barrel, and don't be surprised if they take a bit more powder.

 

[Rick H]

I have Moly'ed my 7mm RemMag hunting load since the mid 80s (Hornady 162 BtSp) I clean my bore after use with kroil and occasionally J&B compound. It has a couple of thousand rounds through the barrel with no apparent loss of accuracy, velocity, or corrosion.

My Load is VERY hot according to modern loading manuals. ( a full 7gr over modern maximum and one grain over the load published on the last 8lb jug of powder I purchased) It was listed as maximum for H-4831 in the manuals from the late 70's and early 80's. When I developed the load I did not have a chronograph. The load shot well, I got 5-7 loading before getting case neck splits and with no outward appearance of pressure problems.

When more modern data started calling for less powder as maximum I decided to try Moly. I have since purchased a chrono and my load, moly coated, is doing 2965 fps. It is flat shooting, accurate, and the bullet hits like the hammer of Thor. I have no intention of changing it until I burn up the 6 lbs or so of powder from the jug I have.

So, your use may differ, but it works for me, and my 700 Remington appears no worse for wear. No moly build up in the bore, no corrosion, and the last time I checked zero it printed a 3/4" 3 shot group, at 200 yds. I am not going to change a thing.

 

[Mowgli Terry]

I have recently bought batches of broken boxes of bullets. There are some moly coated bullets included. These are bullets still on the market less the coating. Removing the coating will remove a variable.