Audax wrote:6.5x55ai wrote:How does it extend the life of the barrel as it won't prevent throat erosion, the main killer.
Exactly....you need more powder with moly and we know or should know hotter loads burn barrel throats quicker than lighter loads...can't see how moly or any other coating that requires more powder will stop or minimise firecracking, and throat degradation in any way.
I think you need to carefully define "hotter loads". It may be more powder but only to get back up to original velocities, ie similar pressures (which may occur later and therefore further down the barrel.. Whether that's due to reduced friction or, as Alan suggests, a slower burn, it is essentially "the same" load.
We can also examine what moly does about fire cracking. A naked bullet will fill those cracks with carbon. You are then pushing a bullet over steel and carbon. With molly filling the cracks, and coating the barrel the bullet continues to run on molly all the way.
All just theory and I've only ever mollied 308 so can't really comment on extended barrel life. All I can say is it certainly doesn't shorten it