From the Benchrest List:
Molybdenum disulfide's claim to fame as a lubricant is that it works
under HIGH pressure where most other
lubricants would break down (and, yes, it does have a low coefficient
of friction, too). 0.3 micron diameter particle
moly (I believe, one of the highest grades of moly) has a working
pressure of 500,000+ PSI at -100 to +1000
degerees F. (Data from Parsec's specifications for the moly
that they use in their moly containing products.) I would imagine
that the pressure between the bullet and rifling JUST as they meet, as
engraving starts, is pretty darn high.
J. N.