06-25-2013, 10:21 PM
(This post was last modified: 06-25-2013, 10:33 PM by babaganoush.)
KentuckyBuddha Wrote:Wouldn't 1/8 be fine for 20" and maybe not quite enough for for 16"... and maybe even 1/9 might be enough for some even as short as 20" and certainly longer barrels might stabilize enough at the slower twist when it comes to 140 grain pills? The extremely low drag in those big bullets made me do a whole lot of hand wringing about what I want. I might be off base. : shrug :
KB - The twist rate really has nothing to do with the barrel length. Rather, it has to do with the Bullet Length, in proportion to its diameter. The essentials are that, for a given bore, heavier bullets are longer and, as a result, need a greater twist rate to stabilize them. It has nothing to do with the distance or time spent going down the tube (barrel length), but has everything to do with the rotation speed (twist rate). That's why pistols (~3-6" barrels) can typically run around 1:16 twist for those short, stubby .40's and .45's. (They are shorter, compared to their diameter, than most rifle rounds.)
In other words, no matter the barrel length, if you're going to shoot the 140's, you need the faster twist rate in order to ensure they are sufficiently stabilized.
David
"A problem thoroughly understood is always fairly simple. Found your opinions on facts, not prejudices. We know too many things that are not true."
Charles F. Kettering