October 15th, 2012
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.
You 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.”
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.
To learn more about the metals used in your firearms’ barrels, rings, receivers, and internal parts, read Sweeney’s article in RifleShooterMag.com. 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.
October 9th, 2010
Many of our readers tell us: “I love the challenge of shooting paper in Benchrest, F-Class, or High Power matches, but it would be fun to get some buddies together and ring some steel at multiple distances.” Well, if you’re in America’s heartland, here’s a place to go. Young’s Longshot Range, in Woodruff, Indiana, is a veritable “Disneyland of Steel”, with a huge variety of reactive metal targets set at yardage-marked berms from 25 to 1000 yards. Indiana’s only 1000-yard facility, Young’s Longshot Range is open 365 days a year. It has outdoor shooting stations (both covered and uncovered), PLUS a heated building with drop-down windows for winter shooting. There’s even a raised 5 meter high platform for prone shooting.
Big thanks to Michael Sorensen (below) for this report and range photos.
June 25th, 2009
California Varmint Silhouette matches are the focus of our current main feature story on AccurateShooter.com. After reading that story you might say: “Looks like fun, but how can I avoid going downrange everytime I knock down the targets?” Well, if your club already has a fixed steel plate or a gong at 500 or 600 yards, you can just shoot at it and look for the “splash marks” from bullet impact (if you can’t hear the hit). Bring a can of white paint and re-paint the target every so often. Shooting range steel is fun, but we’ve found most of the “semi-permanent” long-range steel targets at clubs are pretty large. You want something more the size of a varmint to provide a better challenge. You could set out some clay birds of course — but again that requires you to traipse down-range every dozen rounds or so.
Affordable Self-Resetting Armored Poppers
To duplicate the fun of a varmint silhouette match, we recommend self-resetting pop-up targets. These are sold by LV Steel and other target makers. Contructed of “AR500″ hardened steel, the LV poppers are rugged and very durable. The armored LV Steel targets can stand up to repeated hits from a 300 Win Mag. Shown below is LV Steel’s #4 (10″ x 6″) spring-loaded “paddle” popper. The video shows it soaking up repeated hits from a 300 Win Mag at 100 yards. Such self-resetting poppers are small enough that you could carry 2 or 3 in your car or truck easily. That way you can set up your own long-range “steel challenge” whenever you go shooting. The same poppers can also be used for pistol practice. LV Steel’s #4 paddle, made of 5/8″-thick steel, costs $150.00 and is designed to ship in a UPS flat-rate box. LV Steel makes a wide variety of other metallic targets.
May 17th, 2009
John Krieger is widely recognized as one of the wizards of barrel-making. Krieger cut-rifled barrels are widely recognized as among the best you can buy. You’ll find Krieger barrels winning in all major disciplines, from “point-blank” benchrest to 1000-yard prone matches. John Krieger, and his staff of highly-skilled employees, are strongly committed to quality manufacturing and customer satisfaction. When asked to describe his “business philosophy”, John stated: “Everybody in the company has one concern. That’s just to make the best barrels we can make — hopefully the best barrels that have ever been made — and to try and keep (as much as humanly possible) every customer happy.”
During the NRA Annual Meeting, we had a chance to chat with John Krieger. John shared his views on a variety of technical topics, ranging from gain twist rifling, to advances in steel quality and manufacturing methods. John answered questions about barrel contours, barrel fluting, and stress relieving. John also provided some sage advice on how to protect your barrel’s crown during the cleaning process.
March 24th, 2009
The National Shooting Sports Foundation (NSSF), in partnership with the United States Practical Shooting Association (USPSA) has launched a new pistol-shooting discipline for high school and collegiate shooters — the Scholastic Steel Challenge (SSC). The Scholastic Steel Challenge program is being modeled after the highly successful NSSF-developed Scholastic Clay Target Program. The NSSF will help launch this new discipline with a $50,000 grant to the SSC, administered under the USPSA.
SSC Format Based on Steel Challenge
The SSC competition format is based on the Steel Challenge, a popular action pistol competition that attracts some of the world’s best shooters. The scholastic version has been designed so it can be enjoyed by both novices and experienced shooters. Competitors will engage targets from a low-ready position and not from holsters as is done in the Steel Challenge.
SSC Will Have Two Divisions: Junior (Age 14-16) and Senior (Age 17-20)
SSC is open to all eligible youth shooters. There is a Junior Division for 14 to 16-year-olds and a Senior Division for 17 to 20-year-olds. Scores and rankings will be posted online, and championships will be awarded in both divisions.
“We thank the NSSF for its support and for providing an outstanding model for our Scholastic Steel Challenge program,” said Scott Moore, director of SSC. “Our goal is to introduce the thrill and action of shooting steel targets to the youth of America through a program that is grounded in safe gun handling principles.”
“Developing new target shooters through programs that teach safe and responsible handling of firearms is a priority of the National Shooting Sports Foundation, and we’re proud to help a program get off the ground that holds so much potential for introducing new shooters to a lifetime sport,” said Steve Sanetti, NSSF President.
August 25th, 2008
Some folks feel that they don’t have to worry about rust and corrosion on stainless steel barrels, actions, and other components. That’s not really true. “Stainless” is a bit of a misnomer. First, there are different types of stainless steel alloys, with different degrees of rust resistance. 300 series stainless is more corrosion resistant than the 416 stainless commonly used in barrels. The composition (by percentage weight) of 416 stainless is 0.15% carbon, 12-14% chromium and the rest iron. 416 stainless steel lacks the roughly 10% nickel content that makes the 300 series more corrosion resistant in atmospheric conditions.
Though some grades of stainless are more corrosion-resistent, ALL varieties of stainless steel can rust if they are not handled and stored properly. Forum reader Kells81 observed: “Wanna see some rusted stainless? Go to the big “C” brand store in Ft. Worth. Every stainless gun they have on the used gun rack is rusted.” Tom Easly of TRE Custom explains: “Sweat is very corrosive. Sweat and blood will rust many stainless steels. I hate to handle my guns or drip on them when I sweat. It really helps to just wipe them good with a wet rag, dry and wipe on a light coating of gun oil. I think most stainless barrels are made from type 416 stainless, and it is generally pretty corrosion resistant, but not when exposed to sweat, blood, or chlorates (corrosive priming), and some other electrolytes.”
Forum member Jacob, who is studying materials science at LSU, provides this technical information: “The basic resistance of stainless steel occurs because of its ability to form a protective coating on the metal surface. This coating is a ‘passive’ film which resists further ‘oxidation’ or rusting. The formation of this film is instantaneous in an oxidizing atmosphere such as air, water, or other fluids that contain oxygen. Once the layer has formed, we say that the metal has become ‘passivated’ and the oxidation or ‘rusting’ rate will slow down to less than 0.002″ per year (0.05 mm per year).
Unlike aluminum or silver, this passive film is invisible in stainless steel. It’s created when oxygen combines with the chrome in the stainless to form chrome oxide which is more commonly called ‘ceramic’. This protective oxide or ceramic coating is common to most corrosion resistant materials.
Halogen salts, especially chlorides, easily penetrate this passive film and will allow corrosive attack to occur. The halogens are easy to recognize because they end in the letters ‘ine’. Listed in order of their activity they are: fluorine, chlorine, bromine, iodine, astatine.
These are the same chemicals that will penetrate Teflon and cause trouble with Teflon coated or encapsulated o-rings and/ or similar coated materials. Chlorides are one of the most common elements in nature and if that isn’t bad enough, they’re also soluble, active ions. These provide the basis for electrolytes. The presence of electrolytic solutions can accelerate corrosion or chemical attack.”
CONCLUSION: Stainless steel barrels and components won’t rust nearly as fast as blued steel, but you still have to take precautions — particularly removing sweat and corrosive salts from the barrel. Also, don’t let moisture build up inside or outside of the barrel.
We recommend wiping your barrels and actions with Eezox, or Corrosion-X after each use. These are both extremely effective rust-fighters that go on thin, without leaving a greasy residue. (Eezox leaves a clear finish, while Corrosion-X has a slightly waxy finish.) Also store your guns in Bore-Store synthetic bags when the guns go in the safe. Bore-Stores wick away moisture, and the synthetic fleece inner surface is treated with rust-fighting chemicals. Bore-Stores also protect your guns against dings and scratches. To discuss rust formation on stainless steel, visit this FORUM Thread.