Could someone explain to me the differences between chrome moly and stainless steels in regards to a barrel?  For example, which is better for certain situations.

Thanks,
- Nick

Chromium-Molybdenum steel alloy and "stainless" steel alloyS are steel alloys that have different elements in their compositions. The stainless alloy(s) used for rifle barrels have good (not perfect) resistance to corrosion and are easier to machine than "chrome-moly" steel.The chrome-moly steel barrels have been around for some time and barrel makers are very experienced in using this alloy. Either alloy will make a barrel that will exceed your abilities to use it. Either alloy will deliver precision shots for about the same number of times. The things that will affect the barrels the most are: 1) The skill/quality of the manufacturer. Barrels are definitely what you get is what you pay for. 2) The use of the barrel. High flame temperature (read as double base), heavy charges, heavy projectiles, and high velocities all will toast a tube early. 3) Your care, cleaning, and storage will prolong or shorten the barrels life (rust and corrosion). Personally, for a weapon barrel, I never cared for a shiny barrel (on the outside).

Thanks ArmyOrdGuy, I'm building a varmint AR and I'm trying to figure out which type of barrel ("stainless" or Chromoly) will suit my varmint hunting needs better.  Most of the time I will be taking slow accurate shots, but I'm sure the barrel will get very hot so it would be nice for it to resist heat reasonably well!

Thanks again, Nick

Heat "resistance" is undefined. A metal part will have a "specific heat" property that depends on its composition. For stainless or chrome-moly, there won't be much if any difference. A light weight barrel will heat up (and cool off) much faster than a heavy barrel because there is less material to store the heat in. The hotter the barrel, the greater chance for it to warp. A dark surface radiates heat faster than a light colored surface. Greater surface area radiates heat faster than a lesser surface area FOR PARTS OF THE SAME MASS. For your application, get a heavy barrel and , if you feel rich, get it fluted. Either alloy would be acceptable; however, get a name brand barrel.

There used to be all sorts of things said about stainless barrels.  One was that they could not withstand heat, or held the heat longer.  That has not been my experience.  Half of my firearms have stainless barrels.  Of my AR's, I have, or have had, an Oly Ultramatch barrel (1" bull), a 20" heavy barrel (HBAR contour), and a 16" heavy barrel.  

Stainless vs chrome moly vs chrome lined just does not seem to be much of an issue for me.  I like the corrosion resistance of stainless.  That is an important factor in my high humidity area.

I am also not convinced that chromelined bores are less accurate for the average shooter.  Perhaps for a benchrest or varmint shooter, but not for the average guy for general use (plinking, homeland defense, target).

I don't baby my stainless firearms.

My stainless barrels were not shiny.  They are all from Olympic Arms, who put a "black oxide" coating on the barrels.  It is a very deep, flat black, almost the same color as AR15 receivers.  It is also durable.  No one who has seen them even suspected they were stainless.

Some manufacturers bead blast their stainless barrels, which imparts a nice non-reflective urban gray color it them.  They blend well with nearly any background, urban or woods.

Varmint hunters usually prefer free-floated fluted bull barrels, which are usually stainless.

Mine has a flattop receiver with free float tube, topped with a Leupold 6.5-20x Vari-X III.  The barrel is an Olympic Arms 20" Ultramatch stainless bull barrel, a hair under 1" dia, with 1 x 8.5" twist, JP trigger and speed hammer, and Harris bipod.

My stainless 16" barrel is more of a pain in the ASS to clean than my 16" Chrome lined barrel!  Very similar accuracy, just not as fun to get dirty (and clean).

 Just my take on it though...