Twist and velocity

[jericho]

Good morning all

So I was watching a CSI:NY episode last night and there one of the characters was going on about how the bullet in said victim did not have enough velocity 'cause home made weapon had no rifling so bullet just rattled down barrel.As far as I understood,in simple terms no rifling wont affect velocity? A good fit of bullet in barrel will have more of an impact? I understand that there is a relationship between weight(actually length) of bullet and twist.

Am I right or am I missing something.

[MontanaRifleman]

Jericho,

Twist is basically detrmined by the cal-to-length relationship of the bullet. Velocity will have an impact as well. So basically, the longer the bullet in a particular cal, the tighter the twist required and the great the velocity, the less twist required.

-MR

[jericho]

Thats the one part I do understand. They were saying the absence of rifling is what decreased the velocity. I thought some of the older muskets( pre rifling) when packed and charged well gave comparable velocities to some modern day rifles.

[MontanaRifleman]

That is beyond my knowledge and understanding, so I cant help you there.

[J E Custom]

Originally Posted by jericho

Thats the one part I do understand. They were saying the absence of rifling is what decreased the velocity. I thought some of the older muskets( pre rifling) when packed and charged well gave comparable velocities to some modern day rifles.

Remember this is TV.

My understanding of the theory is that if the bullet is a good fit it would be faster than if it
was not. But it would have more drag due to the increase in surface area slowing it down
a little. But a sabot with a good seal and of the same weight would be the fastest with
everything else being the same.

If a weapon was worn out and didn't have any rifling left it would have a lot of blow buy
and would be slower, But I have never seen a rifle with all of the rifling gone. I have looked
down the bore of rifles with over 75,000 rounds through them and they still had rifling
but 4 or 5" of throat was gone.

The old muskets used smaller round balls slightly smaller than the bore so they could be
patched with cloth or paper to seal the bullet to the bore and improve the loading process.

J E CUSTOM

[jericho]

I did fail to mention that said gun was a home made gun made out of some metal tube hidden in a pen. I never took it too seriously from the beginning. Its still an entertaining show though.

[trebark]

I had to stop watching CSI when I saw an episode where the victim was killed with a frozen beef bullet.

Yes, the criminal stuffed ground beef into bullet cast. Froze it, then loaded it into a cartridge. Then proceeded to keep the bullets frozen until moments before shooting the victim. It should be mentioned that the crime took place far from any building or electrical source (read: refrigeration).

So anytime someone says CSI...I say....Frozen Beef Bullets!