Why are barrels rifled

It also results in an improved finish, with an Ra significantly lower than either the original bore, or other rifling methods. Because no metal is cut, manufacturers and operators do not have to manage chip control.

Button rifling is also a highly controlled process that is repeatable across an entire production lot. 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. Advancements in modern machine design and the use of servo technology allows operators to easily program a gain twist with the same tool, while modern CNC technology enables a simpler, more repeatable operation.

Cons of Cut Rifling - Cut rifling is a very time consuming process due to the number of cuts and minimal amount of material removed per cut.

It does require a skilled tradesman to operate the machine and process parameters as compared to other rifling methods, where variables are highly controlled by the machine. Repeatability is hardest to maintain with cut rifling. TFB covers top stories in the firearms industry. TFB staff writers share a passion for firearms but come from a diverse background, stretching from the world of law enforcement to being deployed on the streets of Fallujah, Iraq to the woods hunting wild game. For the latest Police1 firearms product articles, check out a modern duty pistol for small cops , 10 families of great concealed carry firearms and our review of rail-mounted lights and lasers.

More Product news. More Product Originals. More Police Firearm Accessories Articles. All Distributors. More Police Firearm Accessories Deals. Make Police1 your homepage. Download a brochure now! Police Products Police Firearm Accessories. Email Print. Thank You! To confidently match a fired bullet back to one gun, the rookie forensic examiner must learn where to look for true unique markings transferred to a bullet.

Carry-over marks from one barrel to another are infinitesimally rare. Carry-over marks will show in the grooves of the barrel. They are typically larger than the normal striations relied upon for comparisons, not to mention being blatantly atypical.

We easily avoid tooling carry-over problems through experience, careful consideration of the entirety of the set of markings, and focusing on areas that contacted the lands of the barrel. Toolmarks on the lands are created by the bore drilling operation and run perpendicular to the axis of the bore. Even in hammer-forged rifling, it is the remaining drilled surface that makes unique toolmarks.

In addition, less dramatic actions—like removing the mandrel and crowning the muzzle—can impart unique toolmarks. A cast bullet shooter probably wants deeper grooves, but beyond that, any of these methods will produce a barrel that will out-shoot most shooters. Give a Gift Subscriber Services. See All Special Interest Magazines. All Shooting Times subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow. Get Digital Access. Subscribe To The Magazine. More Articles From Gunsmithing. Each is interesting in its own way. Rifling is too often taken for granted, but its effect on accuracy represents nearly two centuries of evolution.

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