Reloading moly coated bullets

[gorillamotors]

I have been using the following recipe.

LC 308 brass
Reloader 15 42.0
168g SMK

I just received 500 168g Moly SMK. Do I still use the same 42.0g of reloader 15 or what?

Jim

[Wyoredman]

Moly coating actually reduces pressures and velocities. It acts as a lubricaant between the bullet and the bore, thus there is less friction meaning less pressure. Lower pressure usually means less velocity.

[BDS-THR]

Here's more on Moly coated bullets from The Rifleman's Journal:

Part 1 - http://riflemansjournal.blogspot.com...ma-report.html

Part 2 - http://riflemansjournal.blogspot.com...avid-tubb.html

Part 3 - http://riflemansjournal.blogspot.com...r-bullets.html

Part 4 - http://riflemansjournal.blogspot.com...g-salazar.html

Questions - http://riflemansjournal.blogspot.com...questions.html

[TXAZ]

Moly coating actually reduces pressures and velocities. It acts as a lubricaant between the bullet and the bore, thus there is less friction meaning less pressure. Lower pressure usually means less velocity.

I would tend to disagree. If there is less friction, then the acceleration of the bullet will be greater. As the bullet accelerates at a greater rate, the bullet is further down the barrel than without moly. As a result, the volume for the expanding gas is greater because the bullet is further down the barrel, resulting in the net lower pressure. There may be confusion on what is the cause and what is the effect.

[BDS-THR]

Here's an exceprt from The Rifleman's Journal links:

Briefly we have found that molycoated bullets do:

- decrease pressure by 3-5% depending on cartridge, bullet and powder
- decrease velocity with 0.5 - 1.5% - reduce metal fouling
- increase accuracy under certain circumstances
- very likely increase barrel life

...

Moly is a superb friction reducer and it’s bearing capacity is beyond the yield point of known metals. When a molycoated bullet enters the throat and travels down the barrel it has less friction than a ordinary bullet. So it is not surprising to see a lower pressure. We have not done any huge tests with many calibers but these 3% -5% has been there every time.

If pressure is reduced velocity will also be lower with the same charge. The interesting thing is that velocity is not reduced as much as pressure. Thus, by increasing the charge you can usually get 1% - 2% higher velocity with moly bullets.

...

be careful when using slow powders and moly coated bullets – it is very important the powder charge starts to burn the same way each time. One thing that differ from our testing and some others is that we always use new cases because that is the way loaded ammo is produced (jealous eh?). Sized cases would not be the same. Typically moly reduces the extraction force by 50%.

One explanation for the increased accuracy could be that moly helps the bullet align in the bore. Thus, bullets with long bearing surfaces would not gain much from that help. Pistol bullets in 9 mm have been coated with no effect on accuracy. Probably more factors are involved that we don’t know of at this time.

Much more at links.

[davery25]

interesting. Do you start at the same starting loads using moly bullets?

[1Hobie]

Moly is a problematic coating as it can combine with moisture to create an acidic substance.
http://www.sprinco.com/articles.html
http://www.6mmbr.com/bulletcoating.html
http://www.thehighroad.org/showthread.php?t=651643

Les Baer, exceptional gun maker, told me personally that Moly can wreck a barrel quickly if not cleaned properly.

No advantage is worth the risk.

Hobie

[Gerry]

Moly in the form of molybdenum disulfide powder is a popular and sometimes only option for a lubricant in many industrial applications, including metal forming, dies, stamping and general lubrication in high temperature conditions or where the environment would mess up a wet grease or oil. It's also used in electronics for physical switches and relays, even in aviation systems. I believe before they could make low sulfur graphite, graphite was replaced by moly as a dry lubricant in aviation applications. Moly can withstand high temperatures, and thus even trace amounts of free sulfur are easy to remove.

I've never seen any other sulfur compound or elemental sulfur listed as a trace contaminant in commercial moly powder, so it must be below 20 ppm (parts per million). By law because of the applications in which it is used, dry moly and its preparations sold as a lubricant must have a maximum acid value (KOH MG/G) of 0.5, the same as fuels, oils, greases, and any other products that come in contact with critical metal components that are vulnerable to corrosion over their lifetime.

Here is a typical information sheet for the cheap grade of dry lubricant moly.


Moly powder suppliers often claim that it actually prevents corrosion - not causes it. Imagine the lawsuits if these moly products instead were shown to actually ruin expensive industrial and commercial metal parts by increasing corrosion?

Thus in my opinion that old alarmist article saying how moly turns into sulfuric acid and pits metal is a bit of an exaggeration at the very least. There are no such product warnings for use of dry moly in these critical applications involving metal lubrication, and if there were it could obviously not be used for those applications, particularly where the lives of humans would be put in danger otherwise.

[old roper]

Here something from Berger site on Moly

http://www.bergerbullets.com/Informa...tml#molybarrel

[wingman]

Lost a barrel once due to pitting never used moly again you may or may not experience same.

[old roper]

Walt Berger was pushing Moly mid to late 90's for the BR shooters. I got sucked in only way to do it back then was buy a kit and do it yourself. I could list lot of problems doing it but in the end never saw an improvement in accuracy.