Q & A About Moly Coating Bullets...

[6hold]

I don't know if "MOLY COATING BULLETS" has been all hashed out on this board before or not, I haven't found it, yet. I think Dillon did a fine job of getting most of the pertenant info across in thier article I'm posting below(IMHO). Of course they are advertizing their own products. I haven't loaded for about a decade, so this was all new to me.
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FROM MIDWAYUSA.COM SITE

Moly Questions & Answers

MOLYBDENUM DISULFIDE (MOLY ULTRA-COAT)

Molybdenum disulfide or "Moly", as it is commonly called, is a lubricant used in extreme pressure conditions due to its high degree of lubricity and high melting point. Moly has been found to reduce bore fouling when applied to bullet surfaces. It will decrease bore cleaning effort and time. Published reports have shown an increase in Ballistic Coefficient, longer barrel life, and an increase in accuracy.

Moly coated bullets will reduce pressure and velocity. Loads must be worked up slowly to attain previous velocities, therefore this does NOT mean powder can be added indiscriminately. The maximum pressure of the cartridge must not be exceeded under any circumstances.

LOADING DATA FOR MOLY COATED BULLETS AND NON-MOLY COATED BULLETS IS NOT INTERCHANGEABLE

Below are questions concerning Moly coating that MidwayUSA customers have been asking with technical advice for each:

Do I need steel shot?
A. Steel shot is not needed in the MidwayUSA process.
B. Steel shot is used in other processes as a burnishing aid to imbed the Moly into the bullet surface.
C. By using the MidwayUSA 1292 Tumbler, bullet on bullet impact imbeds Moly into the bullet surface without the use of steel shot.

Do I need carnauba wax?
1. Carnauba wax is not needed.
2. Carnauba wax is used in other processes so the Moly would not rub off the bullets.
3. Some shooters using carnauba wax have found that the wax accumulates in the bore and crystallizes.

How many bullets can I coat?
1. A. An 8 oz container will coat approximately 970 lbs of jacketed bullets or 485 lbs of cast lead bullets.
2. B. The maximum load for a MidwayUSA 1292 Tumbler is 10 lbs.

Do cast lead bullets still need to be lubed?
1. Yes. Even though cast lead bullets have been Moly-coated they still must be lubed after Moly coating.
2. If Midway pre-sized and lubed cast bullets are being Moly-coated freeze the bullets for two hours then tumble with Moly for 20 minutes.

Why do I need different bowls for coating jacketed and cast lead bullets?
1. When coating cast lead bullets or bullets with exposed lead (i.e. soft points, spitzers) a layer of lead is deposited on the surface of the bowl. This layer of lead can then be transferred to a bullet’s copper jacket or plating causing the Moly not to adhere.
2. Bowls used for coating bullets with exposed lead (i.e. soft points, spitzers) should be cleaned after each use.
3. Bowls used for coating cast lead bullets should be cleaned after coating 50 lbs of bullets.
4. Bowls used for bullets without exposed lead (i.e. FMJ, HPBT) should be cleaned after coating 50 lbs of bullets.

How do I clean the bowl?
1. Fill the bowl just above the Moly stain line with corn cob or walnut media.
2. Pour 3-4 tablespoons of bore cleaner into the media.
3. Tumble the media/bore cleaner mixture for 30 minutes or until bowl is clean.
4. Wipe the bowl out with a clean cloth.
5. Degrease the bowl with liquid dish washing detergent and warm water.
6. Some Moly will remain embedded in the plastic bowl; which is perfectly fine. This cleaning process will remove any lead deposited in the bowl.

How pure is MidwayUSA Moly?
1. MidwayUSA Moly is 98.5% pure.
2. Impurities are mostly residual carbon created during production.
3. C. MidwayUSA Moly does not contain graphite. Graphite is hygroscopic and promotes rust.

What is the particle size of MidwayUSA Moly?
1. MidwayUSA Moly is considered to be technical grade. Particle size ranges from 1 to 100 microns.
2. The Fisher rating, or average particle size, is 3 to 4 microns.
How does Moly coating increase velocity?
1. Moly coating actually decreases pressure and muzzle velocity because of reduced friction between the bullet and bore.
2. Moly coating will increase terminal velocity by increasing the ballistic coefficient of the bullet. Moly has higher lubricity than the jacket material. This lubricity causes a reduced coefficient of friction in the air. The reduced drag results in a higher ballistic coefficient.

How do I obtain loading data for moly coated bullets?
1. Load data for Moly-coated bullets is NOT interchangeable with that of non-coated bullets.
2. MidwayUSA does not carry load data for Moly coated bullets.
3. Moly coated bullets will reduce pressure and velocity. Loads must be worked up slowly to attain previous velocities.
4. The maximum pressure of the cartridge must not be exceeded under any circumstances.

I’m shooting Moly-coated bullets and my groups are much larger than they were with non-coated bullets. What’s the problem?
1. It will take approximately 15-30 "fouling" shots with Moly-coated bullets to deposit a thin coat of Moly to the bore. The first coated bullet fired will deposit a small amount of Moly in the bore close to the throat. The next bullet will deposit more Moly where the first left off. Moly deposition will continue towards the muzzle until the entire length of the bore is coated. These fouling shots will provide a sporadic group because of the varying amount of friction in the bore. After the fouling procedure rounds should "settle in" and groups will tighten up.
2. Moly-coated bullets will reduce pressure and velocity. Loads need to be worked up slowly to attain original velocities. Dramatically reduced velocities generally deliver poor accuracy results.
3. It is suggested that loads be chronographed when working up a new load. It will be much easier attaining desirable results with velocity data from your firearm. This is true for all load testing, not just Moly loads.
4. Some non-Moly coated bullet/powder combinations may shoot better than a Moly-coated bullet/powder combination in a specific firearm.

How do I clean my firearm without removing the Moly?
1. Running a dry patch through the bore should remove any fouling; most of which will be carbon fouling.
2. If cleaning with a bore solvent is desired the bore will need to be recoated with Moly. This is accomplished by firing 15-30 fouling shots with Moly-coated bullets.

 

[Gammon]

I was considering treating the barrel of a 38 Super Comp IPSC gun with moly by using coated bullets, even bought a pound of moly. Then I read Wil Scheumann's ideas on the subject and gave up on the idea. He thinks moly could accelerate barrel wear on a pistol used for IPSC competition. Check out his web site.

 

[Scrivener]

I would no more moly coat pistol bullets than I would cast them.

First, most, if not all, of what was in the OP is intended for RIFLE shooters.

Second, handgun bullets don't reach the velocities a rifle bullet does. Even an IPSC "race gun" at a 175 PF is not going to be going much more than 1,400, maybe 1,500 fps; that's HALF of what a .223, .308 or -'06 will be cruising along at.

Besides - my POLY coated bullets have moly in the mix.

 

[BIG GUN]

I bought into the moly kick when Berger first promoted it. What a mistake! I moly'd over 10k jacketed rifle bullets from 22-45 cal. Now I had to start from scratch on my data for 30+ different calibers, plus having to use latex gloves during reloading. Then Berger decided that due to the residule sulfur in the stuff, if any amount was left in the barrel, in conjunction with moisture, it would cause sulfuric acid to form creating major pitting, so cleaning is critical. I still load the ones I have, and use Kroil along with a non imbedding abrasive to clean the bore, and have had no problems, but I will not moly any more when these are gone.
I use the NRA Alox/beeswax old stanby for most pistol & rifle cast bullet's, and as long as you keep the right hardness/velocity ratio, it works just fine.

 

[6hold]

I bought into the moly kick when Berger first promoted it. What a mistake! I moly'd over 10k jacketed rifle bullets from 22-45 cal. Now I had to start from scratch on my data for 30+ different calibers, plus having to use latex gloves during reloading. Then Berger decided that due to the residule sulfur in the stuff, if any amount was left in the barrel, in conjunction with moisture, it would cause sulfuric acid to form creating major pitting, so cleaning is critical. I still load the ones I have, and use Kroil along with a non imbedding abrasive to clean the bore, and have had no problems, but I will not moly any more when these are gone.
I use the NRA Alox/beeswax old stanby for most pistol & rifle cast bullet's, and as long as you keep the right hardness/velocity ratio, it works just fine.

This goes along with "Big Gun" statement above...
FROM RAZOREYE SITE:
http://www.razoreye.net/mirror/ammo-oracle/AR15_com_Ammo_Oracle_Mirror.htm...​

Q. What is Moly? What is it good for?
The term “Moly” refers to Molybdenum Disulphide. This is an extremely fine powder which acts as an inert lubricant between the bullet and the bore. It is coated onto bullets to reduce the friction incurred on the bullet as it passes down the bore. The reduced friction is said to prolong barrel life, increase velocity and the ballistic coefficient, and increase accuracy. The moly coating does not build up in the barrel, as each successive shot removes any excess material from the previous round.
If you are worried about barrel break-in on new rifles, do not use moly to begin with. The extra friction from an uncoated bullet is necessary for proper break-in.

Q. Moly sounds hella-cool. I'm going to use it with all my rounds from now on!
Slow down there chief, Moly isn't sliced bread or anything.
The biggest downside is that Moly is hygroscopic – meaning it is capable of absorbing water from the air. This water is then trapped between the moly coating and the barrel, which is definitely not a good thing. A quick fix to this problem is to run an oiled patch through the barrel after each shooting session. The oil will block moisture from being absorbed.
Moly is also extremely messy, and it likes to stick to everything. It is also easily rubbed off of bullets, leaving a slippery film on whatever it touches. With practice and experience, however, this can be minimized.
The biggest threat to barrel life is not addressed by the use of moly coated bullets: Throat erosion. Throat erosion is not caused by the friction of the bullet, rather the high pressure and high temperature gases that are present in every shot. It is not very often that a rifle barrel wears out it’s rifling before it suffers from extensive throat erosion.