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Civilian AR-15 rifles are commonly found with 1 in 12 inches (30 cm) or 54.8 calibers for older rifles and 1 in 9 inches (23 cm) or 41.1 calibers for most newer rifles, although some are made with 1 in 7 inches (18 cm) or 32 calibers twist rates, the same as used for the M16 rifle. Rifles, which generally fire longer, smaller diameter bullets ...
Conventional eight groove rifling on the left, and octagonal polygonal rifling on the right. Polygonal rifling (/ p ə ˈ l ɪ ɡ ə n əl / pə-LIG-ə-nəl) is a type of gun barrel rifling where the traditional sharp-edged "lands and grooves" are replaced by less pronounced "hills and valleys", so the barrel bore has a polygonal (usually hexagonal or octagonal) cross-sectional profile.
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves ("rifling") cut into the barrel walls.The raised areas of the rifling are called "lands," which make contact with the projectile (for small arms usage, called a bullet), imparting spin around an axis corresponding to the orientation of the weapon.
Most rifle cartridges have a high load density with the appropriate powders. Rifle cartridges tend to be bottlenecked, with a wide base narrowing down to a smaller diameter, to hold a light, high-velocity bullet. These cases are designed to hold a large charge of low-density powder, for an even broader pressure curve than a magnum pistol cartridge.
[36]: 32 The three main class characteristics of all bullets are the lands and grooves, the caliber of the bullet, and the rifling twist. [37] All three can be tied directly to the type of barrel that was used to fire the bullet. [37] The lands and grooves of barrel are the bumps and valleys created when the rifling is created. The caliber is ...
WHAT CAUSES HAIR LOSS? "There are many causes of hair loss, but by far the most common cause is hereditary hair loss with age," Phipps says. "Some men and women have a genetic predisposition for ...
3. Medications. Some medications have been associated with temporary hair loss. Most of the time hair loss related to medication is due to the drug disrupting the hair growth cycle leading to a ...
The cause of male-pattern hair loss is a combination of genetics and male hormones; the cause of female pattern hair loss is unclear; the cause of alopecia areata is autoimmune; and the cause of telogen effluvium is typically a physically or psychologically stressful event. [4] Telogen effluvium is very common following pregnancy. [4]