Troubleshooting .270 failures: why are my bullets keyholing?

Barrel Alignment and Twist Rate

When bullets keyhole in a .270 Winchester, it’s often due to a mismatch between the barrel’s twist rate and the bullet’s design. The .270 Winchester typically comes with a 1:7 or 1:8 twist rate, which is suitable for most hunting bullets. However, if you’re using a slower-twist barrel, it may not be able to stabilize bullets with a higher BC (ballistic coefficient) or those with a larger diameter. For example, a 130gr bullet with a high BC may require a 1:7 twist rate to stabilize properly, while a 150gr bullet might be better suited for a 1:8 twist rate.

Bullet Weight and Profile

Another common cause of keyholing is using bullets that are too heavy for the twist rate or barrel design. In a .270 Winchester, bullets weighing 130-150 grains are generally the most popular choice for elk hunting. However, if you’re using a 160gr or heavier bullet, it may not be suitable for your twist rate or barrel design. Additionally, bullets with a more aerodynamic profile, such as those with a smaller meplat (nose diameter), may be more prone to keyholing due to their higher BC.

Zeroing and Shooting Techniques

Finally, keyholing can also be caused by improper zeroing or shooting techniques. Make sure your rifle is properly zeroed at 100 yards, and that you’re using the correct sight picture and trigger technique. When shooting at longer ranges, it’s essential to use a rifle with a good scope and a stable shooting platform. Additionally, consider using a bullet with a higher BC and a more forgiving design for longer-range shooting.