What does Keyholing Mean in Ammunition?

In firearms and ammunition, "keyholing" refers to a phenomenon where bullets fail to stabilize during flight, resulting in them hitting the target at an angle instead of head-on, with the front of the bullet. This is generally undesired as it reduces the accuracy and the effectiveness of the bullet. When a bullet "keyholes," it creates an elongated hole in the target, resembling a keyhole, hence the name. This irregular hole is a clear indication that the bullet is tumbling instead of spiraling smoothly. There are several potential causes for keyholing:

1. Improper Bullet Diameter: If the bullet's diameter doesn't properly match the barrel's bore diameter, it might not stabilize effectively, resulting in keyholing.
2. Incorrect Twist Rate: Firearms barrels have a specific twist rate that helps stabilize the bullet. If the twist rate is not appropriate for the bullet's length and weight, it can result in keyholing.
3. Muzzle Damage: Damage near the muzzle of the barrel can destabilize the bullet as it exits, leading to keyholing.
4. Suboptimal Bullet Design: In some cases, the bullet design itself might be flawed, making stabilization during flight challenging.
5. Velocity Issues: Bullets that are fired at velocities too low may not gain sufficient rotational speed to stabilize.

To avoid keyholing, it's important to choose the right ammunition for your firearm, considering factors such as the bullet's weight, diameter, and the firearm's barrel twist rate. It's also essential to maintain the firearm properly to prevent issues like muzzle damage.