moly coating bullets

[danptobin]

Does moly coating bullets help barrel life on a 7rum?

[Kirbydoc]

Dan, molybdenum di-sulfide MoS₂ like graphite has a low coefficient of friction , but, unlike graphite it does not rely on absorbed vapors or moisture. MoS₂ also has greater load-bearing ability. MoS₂ has thermal stability up to 2012º F (1100º C) in non-oxidizing environments but in air it may be as low as 662 to 752º F ( 350 to 400º C). In the time those bullets are in the barrel (less than 6 milliseconds in the slowest cartridges out there in a long barrel less than 2 milliseconds in yours even with a 26" barrel) I don't believe the bullet and coating could get that hot. I may be wrong though, wouldn't be the first time. But with that low coefficient of friction it has to help barrel life.

[versifier]

The limiting factor to barrel life is worsening and progressive throat erosion from hot propellant gasses, not the heat of friction from the bullet in contact with the metal of the barrel, am I correct? Question: how can the friction coefficient of the bullet affect the burning temperature of the propellant? I don't shoot magnums and my own experiments tend towards milder cast loads, so I have never really delved into the subject deeply. But it is a really good question. Where is Hatcher's ghost when you need him most?

[danptobin]

Really just wondering if the moly process is really worth the extra time. I want to maximize barrel life not worried about the theoretical velocity gains. Its an ultra mag it goes fast enough on its own.

[Kirbydoc]

Dan,
Versifier makes a great point.
I was not taking into consideration the cartridge you are shooting. I looked up some data and you are probably using between 82 and 103 grains of powder. That is a lot of combustion in a small space! Probably the very best thing you can do to lengthen barrel life is to never let that barrel get really hot. In that huge cartridge Blue Dot shoots he uses about 110 grains and the maker of that rifle advised him to always let the barrel cool between shots. He still only expects about 1,500 rounds give or take out of that barrel before it loses accuracy. I would believe the moly would take a back seat to that advice.

[danptobin]

Thanks Kirby

[j1]

Dan the only cartridge which I coat much is my 223. I think that it helps but I still do not shoot so rapidly that I heat up the barrel.