What Is Barrel Rifling and How Does It Relate to Twist Rate?

By Kat Ainsworth

The rifling in a Glock 19 S3f barrel. (Photo Credit: Christopher Orth)
When selecting a firearm, the term “rifling” often comes into play and sometimes gets caught up in a blanket statement about twist rate. Though twist rates are created by rifling, it’s important to understand the process behind rifling to grasp its importance in the world of shooting.
Rifling History
What makes up rifling — in short, lands and grooves. Lands are the raised, uncut areas of metal while grooves are the lower, depressed portion of rifling. Groove depth varies between .005-inches and .010-inches and is chosen based on what best suits the type of bullet the gun will use. For instance, muzzleloaders require deeper grooves than a bolt-action 6.5 Creedmoor.
Rifling of an AR (Photo Credit: David Werner)
The first instance of well-done rifling can be traced back to 1498 and is credited to the Germans. At that point in history, cutting rifling grooves was far more difficult than it is today; grooves were cut by hand, one by one, slowly and skillfully by gunsmiths to ensure even, smooth results. It took nearly half a century for rifling to transform from a rare art form to today’s where it can be easily mass-produced

Source: Guns.com