March 23rd, 2016

Metal Properties Revealed in ‘Guide to Gun Metal’

Sweeney Guide to Gun Metal

4140, 4150, 316, 17-4, 6061, 7075-T6 — What is the significance of these numbers? No, they’re not winning lottery numbers. These are all designations for metals commonly used in firearm and barrel construction. 4140 and 4150 are carbon steels, with 4150 often used in mil-spec AR15 barrels. 316 and 17-4 are grades of stainless steel. 316 is “marine grade” stainless, while 17-4 has 17% chromium and 4% nickel. 17-4 is a harder steel used in barrels and receivers. 6061 and 7075-T6 are aluminum alloys. 6061 is “aircraft grade” aluminum, often used for rings and trigger guards, while 7075-T6 is a much stronger, heat-treated aluminum commonly used in AR15 uppers.

Sweeney Guide to Gun MetalYou can learn about all these metals (and more) in the online archives of RifleShooter magazine.

Written by Patrick Sweeney, RifleShooter’s Guide to Gun Metal summarizes the primary types of steel and aluminum used in gun and barrel construction. Sweeney explains the nomenclature used to define metal types, and he outlines the salient properties of various steel and aluminum alloys. This is a useful resource for anyone selecting components or building rifles. We recommend you print out the page, or at least bookmark it.

Metals by the Number
The number system for steel classification came from the auto industry. Sweeney explains: “The Society of Automotive Engineers uses a simple designating system, the four numbers you see bandied about in gun articles. Numbers such as 1060, 4140 or 5150 all designate how much of what [elements are] in them. The first number is what class—carbon, nickel, chromium, and so forth. The next three numbers [list other elements in the alloy]. 4140, also known as ordnance steel, was one of the early high-alloy steels. It has about 1 percent chromium, 0.25 percent molybdenum, 0.4 percent carbon, 1 percent manganese, around 0.2 percent silicon and no more than 0.035 percent phosphorus and no more than 0.04 percent sulphur. That leaves most of it, 94.25 percent, iron.”

Aluminum Alloys
Numbers are also used to differentiate different types of aluminum alloys. Sweeny writes: “Aluminum is used in firearms in two alloys: 7075 and 6061. 6061 is commonly referred to as ‘aircraft aluminum’ and has trace amounts of silicon, copper, manganese, molybdenum and zinc. 7075 is a much stronger alloy and has markedly larger amounts of copper, manganese, chromium and zinc.” 7075 Aluminum has significantly better corrosion resistance, and that’s why it is used for AR receivers. The “T6″ you often see appended to 7075 refers to a heat-treating process.

Aluminum (or “Aluminium” in the UK) is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal. Aluminum is the third most abundant element, and the most abundant metal, in the Earth’s crust. (Wikipedia)

Aluminum alloy table chart Silicon Maganese Zinc Copper Magnesium

To learn more about the metals used in your firearms’ barrels, rings, receivers, and internal parts, read Sweeney’s article in Taking the time to read the article from start to finish will expand your knowledge of metal properties and how metals are chosen by manufacturers and gunsmiths. CLICK to Read Guide to Gun Metal.

Story Tip by EdLongrange. We welcome reader submissions. Aluminum Alloy chart courtesy
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March 23rd, 2016

Resources Explain Gun Laws in All 50 States

Gun Laws by State Brian CiyouMany of our readers travel far and wide during summer months, both on family vacations and to participate in shooting matches. When transporting firearms across state lines, it is vital to understand the laws and regulations that apply in each jurisdiction. Moreover, all of us need to stay informed about gun laws in our home states, since new laws are passed every year.

Indiana attorney Brian Ciyou has created an outstanding resource, Gun Laws by State (2016 Ed.) (GLBS), that explains firearms laws in all 50 states. Ciyou’s gun law treatise, available in both book and online (web) formats, covers state laws as well as key federal laws that apply in federal buildings, airports, National Parks, and school zones. There is a handy Reciprocity Map showing which states recognize concealed weapon permits issued in other jurisdictions. Moreover, GLBS covers Reciprocal Carry for all 50 states, Constitutional Law, Federal Statutory Law, Use of Force, Criminal Provisions, Civil and Criminal Liability, Preemption, Federal Property Rules, and Interstate Transportation.

Gun Laws by State Brian CiyouAmazingly, you can access all this important legal information for FREE on the GLBS website. Click on an interactive map to quickly review gun laws in any state. Navigation links provide quick access to particular topics, such as rules for Airline Travel, Amtrak, National Parks, and Federal properties. The web version of Gun Laws by State is updated regularly, and Ciyou even provides a GLBS Gun Laws Blog with current “news and views” on gun regulations nationwide. I suggest readers bookmark the site, and consider buying the book if you frequently travel with firearms outside your home state. The printed book version costs $19.95, while a digital eBook is $9.95 (or you can get both for $24.99). Click here to purchase GLBS books and eBooks.

WATCH Gun Laws by State Introduction Video

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