Steel alloys in firearms production doesn’t exactly scream exciting as far as reading material, but it is a relatively interesting topic. Outside of the entertainment value, it is something that the average gun owner and certainly those in the firearms industry should have a fair knowledge of. In the following discussion, we’ll take a look at some of the various alloys being utilized in current firearms manufacturing and the benefits and longevity they contribute to the end product.
Before we move into discussing the various alloys, let’s first talk a little on identification. It’s likely that at some point you’ve noticed a string of four numbers after the steel title. These four numbers come from the Society of Automotive Engineers simple designation system and provide insight into the makeup of the steel itself.
The first number indicates the class of steel. The next three numbers indicate what is in them with the last two numbers indicating the carbon concentration down to a single percentile. For example, the 41 in 4140 would indicate a Chromium Molybdenum Steel (MBD) of which you can look up the specific makeup, and the 40 in 4140 indicates 40% carbon. Of course, the remainder of the metal is iron.
Stainless steel has its own designation and system and therefore will not fit this cataloging style but is one more area that you can explore. It is also worth noting that you can occasionally run across proprietary blends with names or numbers that do not align with this practice as the manufacturer has chosen to keep the actual mix confidential such as the Carpenter 158 which is the mil-spec for AR bolts. Understanding this simple identification process, you can now quickly determine the type of steel alloy your working with or contemplating purchasing. But, this just tells us the ingredients, and while it is a good starting point, it is only one piece of the puzzle.
Now that we know what type of steel we’re dealing with, we need to understand better the benefits and differences of those and how they impact our firearm construction. The advent of the modern cartridge and continual evolving of ammunition powder and loads has brought about the requirement for more durable firearms. Due largely in part to the higher pressures, the parts are exposed to. Fortunately, metallurgy and production have also advanced in unison, and our modern alloys and treatment processes allow for a stronger, longer, and more resistant firearm.
Manufacturers now have the expertise and ability to tweak and modify steel alloys to best fit the particular component requirements as well of course incorporating production and profit potential in the equation. If say a part requires a great deal of strength and flexibility like a barrel they can opt for an alloy such as 4150 which contains a good carbon ratio to provide the extra mil-spec durability they are wanting. Another great option for the manufacturer is hardening. Say in the case of our 4150 it is a great steel for the barrel but not as corrosion resistant or hard as stainless steel. To overcome this the manufacturer can harden the steel allowing the internal makeup to remain the same while the external surface provides a more durable state.
As you can see from the above the ability to combine ingredients, mixing process, and treatments allow for virtually any combination of requirements to meet the manufacturing needs. Of course, this is only a short primer on a very complex topic, but with a little research, you can ensure your next purchase is perfect for your intended purpose.
Do you have any thoughts on the matter you’d like to add? Feel free to share in the comments below!