The weapon's rifling has how many lands and grooves and what is the twist direction and rate?

The weapon's rifling has how many lands and grooves and what is the twist direction and rate?

• 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 8 inches
• D. 5 lands and grooves, 1 uniform right-hand twist every 12 inches

Answer: (B)

Rifling characteristics describe how the bore imparts spin to the bullet. The number of lands and grooves tells you how many spirals there are around the bore; three lands and grooves means the bore has three such features, with three corresponding raised lands. The twist direction indicates how the rifling twists as the bullet moves from chamber to muzzle—the left-hand twist spins the bullet counterclockwise as it exits. The twist rate is the distance along the bore for one full 360-degree rotation; a 12-inch twist means the bullet completes one turn every 12 inches of barrel. So, a bore with three lands and grooves, a uniform left-hand twist, and a 12-inch twist rate describes the combination given. The other options would imply different numbers of lands and grooves, a different twist direction, or a different twist rate, which would not fit the described rifling.

Rifling characteristics describe how the bore imparts spin to the bullet. The number of lands and grooves tells you how many spirals there are around the bore; three lands and grooves means the bore has three such features, with three corresponding raised lands. The twist direction indicates how the rifling twists as the bullet moves from chamber to muzzle—the left-hand twist spins the bullet counterclockwise as it exits. The twist rate is the distance along the bore for one full 360-degree rotation; a 12-inch twist means the bullet completes one turn every 12 inches of barrel.

So, a bore with three lands and grooves, a uniform left-hand twist, and a 12-inch twist rate describes the combination given. The other options would imply different numbers of lands and grooves, a different twist direction, or a different twist rate, which would not fit the described rifling.