What causes bullets to spin when fired from a rifle or handgun?

• A. Rifling
• B. Barrel length
• C. Bullet weight
• D. Powder charge

Answer: (A)

The spin comes from rifling. The inside of a gun barrel has helical grooves that twist as the bullet moves through it. As the bullet engages these grooves, it is forced to rotate, gaining angular momentum. That spin acts like a gyroscope, stabilizing the bullet in flight so it stays nose-forward rather than tumbling. The rate of twist in the barrel (how fast the grooves turn) helps determine whether a particular bullet will stabilize properly.

Barrel length, bullet weight, and powder charge influence velocity and energy, but they don’t directly cause the bullet to spin. Without rifling, a bullet would shed stability and wobble in flight; with rifling, it gains the spin needed for accurate, stable flight.