Gun-maker Bear Creek Arsenal has a good article on its website about rifling barrels. The article explains four common methods of rifling the interior of barrels: Cut Rifling, Broach Rifling, Button Rifling, and Hammer Forging. In addition, the article describes a new (and somewhat radical) method, Cation Rifling, which employs acid to etch rifling. READ Full Article.
The main focus of the article is on Cold Hammer Forging of barrels. This requires massive, expensive tooling, but the results can be very consistent. Many top gun-makers, such as FN, HK, and Ruger, have used the hammer forging process. And now Bear Creek Arsenal also offers hammer-forged barrels. Bear Creek recently acquired two state-of-the-art cold hammer forging machines. With hammer forging, a chamber can be formed and barrel contour shaped at the same time. This process produces some of the most consistent barrels available today. Here is a summary of how Cold Hammer Forging works:
Cold Hammer Forging — Machinery and Process
A cold hammer-forged barrel starts life… as a short and fat blank with a polished hole running through the center. A hardened mandrel of proper width (caliber) and rifling pattern — again reversed/inverted — is placed into the smooth bore. The pair go into a forging machine that compresses the steel against the mandrel, hammering it into final shape. The barely detectable external spiral patterns that remain on some barrels are imprints from those hammers at work. Some companies polish them out, however.
Cold hammer forging machinery is very expensive, representing a significant investment for companies. However, when the hammer forging process is done and the mandrel removed, the resulting barrel is the proper length and profile with rifling that is consistent and butter smooth. No lapping is required — a time and expense saver — although a stress-relief step often follows.
The process takes place at room temperature, despite the misleading “cold” terminology. There is a hot hammer forging process, but the equipment is even more expensive and the slight improvement in grain consistency hasn’t proven advantageous enough for a return on that investment. Performance is impressive and consistent.
One of the biggest advantages of a cold hammer forged barrel is longevity. They… survive abuse and last longer. The manufacturing process adds those enviable virtues with each strike of those hammers — strengthening the metal in a work-hardening process employed by blacksmiths for centuries.
Comparing Popular Rifling Methods
What rifling process should you choose? If long-distance is your passion and you home brew custom cartridges to print tiny groups in the next zip code, cut rifling is the optimum choice. Button rifling is a solid second choice, but not always the Holy Grail long-distance shooters dream about. Cold hammer forged barrels, however, last longer and [offer great performance for the price.]
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Gun-maker Bear Creek Arsenal has a good article on its website about rifling barrels. The article explains four common methods of rifling the interior of barrels: Cut Rifling, Broach Rifling, Button Rifling, and Hammer Forging. In addition, the article describes a new (and somewhat radical) method, Cation Rifling, which employs acid to etch rifling. READ Full Article.
The main focus of the article is on Cold Hammer Forging of barrels. This requires massive, expensive tooling, but the results can be very consistent. Many top gun-makers, such as FN, HK, and Ruger, have used the hammer forging process. And now Bear Creek Arsenal also offers hammer-forged barrels. Bear Creek recently acquired two state-of-the-art cold hammer forging machines. With hammer forging, a chamber can be formed and barrel contour shaped at the same time. This process produces some of the most consistent barrels available today. Here is a summary of how Cold Hammer Forging works:
Cold Hammer Forging — Machinery and Process
A cold hammer-forged barrel starts life… as a short and fat blank with a polished hole running through the center. A hardened mandrel of proper width (caliber) and rifling pattern — again reversed/inverted — is placed into the smooth bore. The pair go into a forging machine that compresses the steel against the mandrel, hammering it into final shape. The barely detectable external spiral patterns that remain on some barrels are imprints from those hammers at work. Some companies polish them out, however.
Cold hammer forging machinery is very expensive, representing a significant investment for companies. However, when the hammer forging process is done and the mandrel removed, the resulting barrel is the proper length and profile with rifling that is consistent and butter smooth. No lapping is required — a time and expense saver — although a stress-relief step often follows.
The process takes place at room temperature, despite the misleading “cold” terminology. There is a hot hammer forging process, but the equipment is even more expensive and the slight improvement in grain consistency hasn’t proven advantageous enough for a return on that investment. Performance is impressive and consistent.
One of the biggest advantages of a cold hammer forged barrel is longevity. They… survive abuse and last longer. The manufacturing process adds those enviable virtues with each strike of those hammers — strengthening the metal in a work-hardening process employed by blacksmiths for centuries.
Comparing Popular Rifling Methods
What rifling process should you choose? If long-distance is your passion and you home brew custom cartridges to print tiny groups in the next zip code, cut rifling is the optimum choice. Button rifling is a solid second choice, but not always the Holy Grail long-distance shooters dream about. Cold hammer forged barrels, however, last longer and [offer great performance for the price.]
Share the post "Cold Hammer Forging of Barrels — How The Process Works"
At the IWA Trade Show in Germany a few years ago, a correspondent for The Firearm Blog interviewed Woody Woodall, who runs Lothar Walther’s USA operation. While many shooters assume that Walther hammer-forges most of its barrels like some other European barrel-makers, in fact Lothar Walther USA uses the button rifling technique for most of its US-made barrels.
In the video below, created for The Firearm Blog, Woodall explains that button rifling involves some extra steps to ensure a good result: “The extra work that goes into it is that you’ve got to make rifling, stress relieve it, and have it come out the right size. And it takes a lot of skill to do that. Lothar Walther invented button rifling in 1925, if a better way of making rifling came out, we’d be glad to go to it.”
Woodall explains that hammer forging is a good method for mass production, but it is costly to set up: “Hammer forging is relatively new, it came out in 1934, but did not come into prominence until the 1950s…. But the cost of [hammer forging] in the world today is getting above what the market will bear for barrels. [Hammer forging] is more complicated. As the hammers hit the barrel the barrel gets longer, but the hammers have to hit uniformly so the barrel [stays] straight. There’s a higher failure rate in that. There’s also some surface delamination that can occur, and some other issues. So if you’re hammer forging, you really have to pay attention to the details. So, it’s like button rifling, only ten times more complicated. It’s for super-high-volume production… The large companies tend to use the hammer forging, intermediate size companies tend to use the buttoning, and craft companies tend to use the cut rifling. All three [methods] can make an equally accurate barrel.”
This image shows a barrel in the process of hammer forging. Watch this operation starting at 1:15 in the video linked below.
You have probably heard the term “hammer-forged barrel”. But do you know how the cold hammer-forging process works? In this interesting video from Ruger, you can see the full barrel making process, including cold hammer-forging on a massive machine. Watch long rods of steel barrel material get cut to length, then drilled. After that Ruger uses CNC machines to contour the barrels before hammer forging.
Anyone with an interest in barrel-making should watch this video:
As the barrel is cold hammer-forged, a giant machine literally pounds the barrel from all sides around an internal carbide mandrel, which forms the rifling inside the bore. The actual hammer-forging is illustrated starting at 1:15 in this video. Through the process of cold-working the barrel around the mandrel, the barrel ends up with a longer length, a smaller outside diameter, and a higher hardness.
Before hammer forging, the barrels are deep-hole drilled, four at a time, with a bit that is slightly larger diameter than the caliber planned for the barrel.
Following the drilling, the barrel rod is placed in CNC machines to be turned down to the correct outside shape and size and both ends are trimmed.
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At the IWA Trade Show in Germany earlier this year, a correspondent for The Firearm Blog interviewed Woody Woodall, who runs Lothar Walther’s USA operation. While many shooters assume that Walther hammer-forges most of its barrels like some other European barrel-makers, in fact Lothar Walther USA uses the button rifling technique for most of its US-made barrels.
In the video below, created for The Firearm Blog, Woodall explains that button rifling involves some extra steps to ensure a good result: “The extra work that goes into it is that you’ve got to make rifling, stress relieve it, and have it come out the right size. And it takes a lot of skill to do that. Lothar Walther invented button rifling in 1925, if a better way of making rifling came out, we’d be glad to go to it.”
Woodall explains that hammer forging is a good method for mass production, but it is costly to set up: “Hammer forging is relatively new, it came out in 1934, but did not come into prominence until the 1950s…. But the cost of [hammer forging] in the world today is getting above what the market will bear for barrels. [Hammer forging] is more complicated. As the hammers hit the barrel the barrel gets longer, but the hammers have to hit uniformly so the barrel [stays] straight. There’s a higher failure rate in that. There’s also some surface delamination that can occur, and some other issues. So if you’re hammer forging, you really have to pay attention to the details. So, it’s like button rifling, only ten times more complicated. It’s for super-high-volume production… The large companies tend to use the hammer forging, intermediate size companies tend to use the buttoning, and craft companies tend to use the cut rifling. All three [methods] can make an equally accurate barrel.”
At the 
