October 3, 2021
What is the Best Gun Barrel Metal?
Gun barrels. The majority are made from one single piece of metal; metal that is hard—as in 25 to 32 on the Rockwell C scale of metal hardness.
There are multiple versions of the Rockwell Scale, but Rockwell C is good for measuring hardened metal. This scale is based on the indentation hardness of the metal. It measures the depth of penetration by an indenter into the surface. The hardness is inversely proportional to the depth of the penetration.
Now that we have those details out of the way, let’s look at the metal grades that are most ideally suited for making gun barrels. And we start with the most common metal: carbon steel:
This grade of steel offers high levels of both chromium and molybdenum, which are used as the primary hardening elements. Why is this important? Because both offer high levels of toughness and hardenability. Molybdenum is highly ductile, which helps increase impact properties at high strength.
This grade also contains manganese. While not used as a primary hardening element in carbon steel 4140, manganese increases the strength, hardness, and wear resistance of this metal.
Here’s a bonus to using carbon steel 4140: It has a high level of resistance to corrosion.
This grade is rated 48 on the Rockwell C scale of metal hardness.
This grade is considered a medium carbon and direct hardening steel. This means it offers a good combination of strength, toughness, and hardness after the process of oil quenching and tempering. This also makes carbon steel 4150 highly machinable.