The metal must be harder than the barrel steel, composed of either the best heat-treated tool steel or tungsten carbide. Tungsten carbide is preferred because its high density allows the button to glide smoothly over softer barrel steel, retaining the dimensions of the button longer.
In cross section, a rifling button is the reverse of the desired rifling pattern. High areas on the button press the grooves into the bore; low areas allow cooling fluids to circulate. Chip production is minimal. Cookie Settings Accept All. Manage consent. Close Privacy Overview This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website.
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Necessary Necessary. Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously. The 5R design takes this to the next level accentuating these factors to theoretically increase accuracy and make the barrel easier to clean. Track 2. The design combines standard and polygonal rifling shapes which aims to reduce bullet deformation, escaping gases, loss of pressure… all to allow a more symmetrical movement for a projectile or a straighter line towards the intended target.
Usually it looks like a hexagon or octagon. As an example, polygonal barrels can be found in Glock and HK handguns. Search for: Search. Button Rifling Rifle buttons for 5. Other Types of Rifling The following types of rifling use similar processes as the ones aforementioned.
Progressive twist is possible with the button rifling process. Cons of Button Rifling - With button rifling, an additional stress relieve step is required adding cost and time - the stress relieving operation is used to relieve stress introduced in the bore of the barrel because of the cold forming process. Also, pre-machining of pistol barrel features is not possible, as a uniform outside diameter is necessary due to the swaging performed when button rifling.
A unique tool is needed for every twist, as the helix is ground into the carbide button. Manufacturability - Button rifing is easily done on modern equipment. Servo control of the twist rate, compared to older sinebar or cam technology, has greatly improved the uniformity of twist throughout the barrel, as well as enabled repeatability throughout a production lot.
Availability and relatively lower investment of equipment also makes button rifling an advantageous method. Popularity - Because of the simplicity, consistency, and short cycle time that button rifling offers, this is by far the most commonly used process in rifle barrel manufacturing by volume. Typical Applications - Hunting rifles, MSR style rifles as well as some precision rifles and some pistols.
Video Reference - View the button rifling process. Also referred to as Hook Rifling, this is a metal cutting process that uses a carbide "hook" to cut a single groove in the barrel.
The process requires several passes to cut the groove to its final depth. The tool cuts one of the grooves, indexes, then cuts the next groove and indexes again until the desired number of grooves have been cut. The hook is advanced out or deeper via a wedge type system, and the process is repeated. The whole cycle may include many passes to achieve the final depth of the groove in a barrel. Pros of Cut Rifling - The metal cutting process does not introduce additional stresses in the metal, as compared to a cold forming processes, so the barrel does not require post stress relieving.
Manufacturers have great control over groove depth due to the minimal depth of cut per pass and the number of passes per cycle. By simply running another pass, the groove can be cut slightly deeper to achieve the desired groove diameter.
Because the tools are not specific to a twist rate, manufacturers are able to use a single tool for a range of rifling configurations.
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