How many lands and grooves does the rifling have, and what is the twist specification?

How many lands and grooves does the rifling have, and what is the twist specification?

• A. 4 lands and grooves, 1 uniform right-hand twist every 12 inches
• B. 3 lands and grooves, 1 uniform left-hand twist every 12 inches
• C. 4 lands and grooves, 1 uniform left-hand twist every 12 inches
• D. 5 lands and grooves, 1 uniform right-hand twist every 12 inches

Answer: (A)

Rifling is described by two things: how many lands and grooves there are, and how the rifling twists along the barrel. Lands are the raised ridges, grooves are the cut gaps between them, and the number of lands equals the number of grooves, giving a consistent helical pattern that spins the bullet as it travels. The twist specification tells how tightly that pattern winds; a right-hand twist means the grooves spiral clockwise when viewed from the breech toward the muzzle, and a rate of 1 turn in 12 inches means the rifling makes one complete twist every 12 inches of barrel length. This combination—four lands and four grooves with a uniform right-hand twist of 1:12—is a common, standard pattern, which is why that option is chosen.

Rifling is described by two things: how many lands and grooves there are, and how the rifling twists along the barrel. Lands are the raised ridges, grooves are the cut gaps between them, and the number of lands equals the number of grooves, giving a consistent helical pattern that spins the bullet as it travels. The twist specification tells how tightly that pattern winds; a right-hand twist means the grooves spiral clockwise when viewed from the breech toward the muzzle, and a rate of 1 turn in 12 inches means the rifling makes one complete twist every 12 inches of barrel length. This combination—four lands and four grooves with a uniform right-hand twist of 1:12—is a common, standard pattern, which is why that option is chosen.