Faxon is often asked which barrel material we’d recommend for a given application. Typically, the answer to the question all depends on what you, as the shooter, are going for in your intended build and its application.
Faxon only uses 4150 or 416-R steels in its barrels; the highest grade of each series of steels, carbon and stainless, respectively. The statements mentioned below will generally apply to lower grades of steel 4140 or regular 416, but the shooter should understand the trade-offs to use lower grades prior to selecting them.
First, let’s cover the basics:
4150 or “Mil-Spec” steel is commonly used in heavy-fire applications. This steel is the most common used today by various militaries, including the United States’. It is a high carbon content steel, which makes it resilient to high-heat scenarios and with its abrasion resistance, the barrels wear slower over time.
416-R Stainless Steel is “stainless” steel formulated specifically for gun barrels. 416-R is “stainless” in name only, as it is still susceptible to corrosion but at a reduced pace compared to common steel. Where common “416” gets brittle at freezing temperatures, 416-R is formulated to function in arctic conditions (typically recommended to -40 F). It is ideal for high-precision applications, as the free-machining characteristics of the material are excellent for creating high-definition rifling. 416-R is commonly used where high-accuracy is required.
I want the best accuracy. I should go stainless, right?
Generally speaking, 416-R stainless steel is a better choice for shooter requiring peak accuracy from their barrels. The machining properties of stainless allow it to take a better cut during machining, creating higher-definition rifling, crowns, and chambers.
That said and all things being equal, the differences in performance between 416-R and 4150 are small and many shooters do not see a difference. Skilled shooters however will recognize the small improvements, especially in precision applications.
416-R stainless has reduced barrel life compared to 4150, but will stay more accurate over its usable life.
I’m most concerned about “barrel life.” Which lasts longer?
“Barrel life” is a very difficult standard to measure, as it varies significantly by volume of fire, duration, loadings, bullet materials, etc. As such, Faxon does not formally rate its barrels past stating that we will absolutely stand with any premium barrel in terms of barrel life.
Generally speaking, 4150 steel is a better material choice for military fully-automatic weapons due to its heat mitigation and abrasion resistant properties. 4150 steel can handle extreme temperatures (over 700F) better than stainless.
That said, this applies only to the highest temperatures barrels can reach, which is common only in fully-automatic fire applications. Spirited semi-automatic shooter (even 3-gun), common to civilian applications is not fast enough to get barrels to these extremes.
As such for civilian applications, the difference in barrel life between the two is closer than commonly thought, especially with Faxon’s use of QPQ Salt Bath Nitrocarburization. In civilian applications, steel will last ~30% more round before end-of-life.
It will take 1,000’s upon 1,000’s of rounds to reach the end of usable barrel life.
I live near the sea or in corrosion-prone areas. Which is best?
Contrary to the name, 416-R “Stainless” steel is not more corrosion resistant than 4150 steel. It is a 400-series stainless steel, which is designed more for machining than corrosion resistance than say kitchen pans, silverware, etc.
That said, Faxon QPQ Salt Bath Nitrocarburizes all its barrels, which drastically increases corrosion resistance across all environments. Both types of barrel will work well.
I’m just building my first AR and looking for a good “all-around” barrel. What fits best?
For first-time builders or those building “all-around” weapons, Faxon recommends 4150 steel.
I’m a high-volume 3-gun competition shooter, what about me?
If your focus is on accuracy, go with stainless. Even across aggressive courses of fire, stainless will provide excellent results.
If the focus is on barrel and parts longevity, 4150 will be a better choice.
I shoot suppressed. Which works best for that application?
Both materials will perform well suppressed. Pick the profile the best suits your application.