Types of Barrel Materials

The one question I see on more AR-15 forums is “what is the best barrel”? And the answer to that question is as varied as the types of barrels that exist for the AR-15.

So I thought it’d be fun to take a look at the various types of barrels and what they’re best used for…

Please note that it is impossible for me to tell you what the “best barrel” is. I can only tell you what the “best barrel” is for what YOU want to use it for.

With that being said, we need to first examine the materials that barrels are made from:

Show Me What You’re Made Of
First, the Chrome-Moly-Vanadium, or CMV. CMV barrels are great for the average shooter, or anyone looking to get their first AR-15. You won’t go wrong with a chrome moly barrel!

And even with this type of barrel steel, you’ve got options!

Most CMV barrels are made from 4140 steel. The general view is that this type of steel is more thermally stable. Essentially, when it gets hot, the molecules have a tendency to stay in one place (but that’s really any 4000-series steel).

The other type of CMV steel is 4150. This is the steel used by our Armed Forces, believing it’s better for full auto. It’s slightly harder, with a higher chromium count and therefore more rust-resistant.

Truthfully, you won’t notice the difference between the two. The US military uses 4150 because their guns are used in combat. They push the barrels to the ragged edge of what they’re made for. But for most shooters, either steel type will work just fine.

Next, let’s look at Stainless Steel.

Stainless barrels have a higher Rockwell hardness (38-42) than a chrome moly barrel (25-30 on average). That makes the barrels harder.
This gives stainless steel barrels a slight edge over chrome moly barrels for accuracy. In fact, any firearm championship of recent note has been won using a stainless steel barrel.

Stainless steel barrels, contrary to popular belief, aren’t sought after SOLELY for their improved accuracy. Rather, the stainless steel allows the barrel to maintain its shape during shooting. Overall, it has a slight edge in accuracy and wear durability.

And in the shooting world, “slight” is relative (usually 5-10%). “Slight” is also important.

There’s a reason why premium gun manufacturers choose stainless barrels over chrome moly.

You’re paying for the edge.
You’re paying for the higher quality.
You’re paying for the 5-10% “slight” improvement.

Because when you start adding “slights” from all over the barrel (slight improvement from the barrel, slight improvement from the BCG, slight improvement from the trigger, etc)…you start to get not-so “slight” improvements that can mean a WORLD of difference to your aim, depending on what reason, application or competition you need the gun for.

Whether you choose chrome moly or stainless steel, this is going to be the base-line for the barrel you want to purchase.

But fear not, weary AR owner. There are still SEVERAL other aspects you’ll need to look at before you pull out your wallet…

Next week, we’ll look at Barrel Rifling – how each method is done and what it means for YOU, the AR shooter.