I am looking into purchasing an SPR Upper or varminter upper for a project which i have in mind. One of the barrels in an upper has a black manganese phosphate finish chrome moly barrel. A stainless steel bull barrel is my 2nd choice as i dont have the time or facilities to undertake a duracoat paintjob for a stainless barrel.  I want to shoot 69, 77 &55 Grain Federal GMM, Hornady T.A.P and Georgia Arms Match ammo exclusively.

I have an elementary understanding of the moly coating concept. I understand that it is a super slick coating which lessens the friction between bullet & barrel and thus extends the life of the barrel. Here are my questions:

-Is it common practice to shoot non moly coated ammo (BTHP, S.M.K, Fed GMM) out of a moly coated barrel?
-What are the advantages/disadvantages to shooting non moly coated ammo out of a moly coated barrel?
-Shooting Non Moly coated bullets out of a moly coated barrel, Will the accuracy & longevity of the barrel deteriorate faster than a stainless bull barrel?

Any insight which can be offered on the subject is greatly, greatly appreciated

adirondack47:

I am kinda having a hard time following you when you talk about a "moly coated barrel".  Are you referring to the "chrome moly".  That is the steel alloy composite of your barrel and not a moly coated barrel.

You can shoot any common bullets through a chrome moly barrel.

Moly coating bullets is a simple process of impact plating Molybdenum disulfide into the soft jacket surface.  Benefits include lower barrel pressures, and reduced copper fouling.  Many also suspect longer barrel life but the process is still to new to know for certain.  Mucho controversy on that.  The only negative arguments that I have ever heard about moly coated bullets is the possibility of moly build-up in the throat area.  I have heard people argue the possibility of it but I have never talked to anyone that has seen it.

My personal experience with moly bullets is that I really like them in a varmint type of rifle for accuracy purposes.  You can shoot all day and your accuracy will not degrade from copper fouling.

Moly bullets in a stainless steel and chrome moly barrel have the same effect.  You can shoot them out of any kind of barrel.

Thank you sir for your insight. Sorry for the confusion, i was referring to shooting non moly coated bullets out of the Chrome Moly barrel.

EDIT: Does a Chrome Moly barrel have any distinct or plausible advantages over a stainless barrel?

Chrome moly is a harder barrel steel than compared to stainless.  It will resist wear a little better than the softer stainless.  How many more rounds?  Who knows.  It depends if the barrel is cut-rifled or button rifled, shooting style (rapid fire or slow), velocity of ammo (more powder=higher velocity=more throat erosion), and accuracy needed at a given distance.  Most service rifle barrels are replaced between 3500-5000 rounds.  They can still shoot great at 300 yds, but 600 scores are hurting.

Stainless is not "more accurate" than chrom moly.  Both can be made to match quality standards.  So the bottom line, the chrom moly may give you a little higher round count.

True cycobushmaster, and I like your explainations.

The only benefit that stainless will have over steel barrels is that stainless has affinity for copper fouling than a chrome moly (steel) barrel so you may have slightly better accuracy after a while.  Stainless will also resist corrosion better than a steel barrel.

Both stainless and chrome moly steel have slight advantages in different areas but they pretty much balance out.  You can't go wrong with either material.  If you want to focus your decision on something, then focus it on barrel quality and maufacturer.  That will make a much bigger impact than chosing between stainless or steel.

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 Cream

Appreciate 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

Thanks 200-10x. I dont want to shoot moly coated ammo as it is less avavilable and more expensive than moly coated ammo. I think that i am going to go with the chrome moly barrel and shoot non moly ammo through it exclusively.