Before we go too far afield.....
Chrome-"moly" barrels have nothing to do with the "moly" coating that goes on bullets. Just like the "Chrome" part of chrome-moly has nothing to do with chrome lining.
Chrome-moly is an alloy. For the most part, if you don't have a stainless steel bbl, you have a chrome-moly bbl.
"Moly coating" a bullet is exactly as expressed by First_LSK. It's often used in competition, less often for varmint shooting. But for the same reasons: lower friction between barrel and bullet reduces pressures, or gives higher velocity with equal pressures; and reduced fouling. As many competitive shooters vouch for it as call it voodoo. The jury could be said to still be out.
Shooting moly coated bullets will eventually coat the inside surface of the barrel as well (which is desired) but will not buildup to "fouling" levels as will straight copper. In fact, if you're going to consistantly shoot moly coated bullets, some people accellerate the process of coating the inside surface of the barrel by introducing "liquid Moly" to the bore before shooting the moly bullets.
Spray Moly or
Moly CreamAppreciate the fact that once you shoot moly, you should not return to std copper jacket bullets.
Here's an interesting series of articles about barrels: Prep, break-in, cleaning and moly coating. Note the Authors, Tubbs, Obermeyer, Krieger.
Jim Owen's "Jar Head Top" website. Jim Owens is a former Marksmanship Team coach. Knows of what he speaks.
You might be interested in the "Final Finish" products, they're pretty cool. You might also check out the Accuracy forum in the General Tab.
Regards - 200-10X