30 Cal Rifling Twist Rate

[Paladinpainter]

Sieger,
I'm going to jump in here and question the notion that an over-spun bullet has a different terminal effect than a normally spun bullet. If the target is 10" thick, a bullet leaving a 1 in 9.84" twist barrel, will rotate about one time before it exits. ( Not tumbling). A bullet leaving a 1 in 20" twist barrel will rotate about half that amount. In either case, and with out testing, I have a hard time believing that one half a rotation of the projectile is significant in any way. Now if the projectile upsets on entry, that might be different. But we're still talking about 1 rotation in each 10 inches of travel.
Regards,
John

[Sieger]

Originally Posted by Paladinpainter

Sieger,
I'm going to jump in here and question the notion that an over-spun bullet has a different terminal effect than a normally spun bullet. If the target is 10" thick, a bullet leaving a 1 in 9.84" twist barrel, will rotate about one time before it exits. ( Not tumbling). A bullet leaving a 1 in 20" twist barrel will rotate about half that amount. In either case, and with out testing, I have a hard time believing that one half a rotation of the projectile is significant in any way. Now if the projectile upsets on entry, that might be different. But we're still talking about 1 rotation in each 10 inches of travel.
Regards,
John

John,

There are several good articles on the net regarding the factors improving terminal effect in meat. Bullet rotation is one of them.

Frankly, with only a 93 grain FMJ bullet, either round nose or truncated cone, I'm inclined to agree with your basic proposition.

Sieger

[Sieger]

Originally Posted by Rick W.

14 Walker

56 Sieger