I had made up some loads for a 40-X in 223 Remington. I had been hung up on trying to get the best performance by using heavy bullets, (hi BC) and working up to the highest recommended muzzle velocity. The two most important parameters in long distance shooting. It completely slipped my mind that I had not considered the barrel twist when choosing the heavy 80 gr bullets.
In the back of my mind was the unrecoverable knowledge that twist is very important when considering the weight of the bullet used! I learned this many years ago on my Colt H Bar Match AR – 15 which has a 1:9 twist but unfortunately in remained forgotten.
Well, you can guess what happened I fired these 80 grain bullets out of the 40-X siting the rifle in. I shot a 5 round “group” and went down range to see the results. Well, they presented me with these beautiful profiles of a sierra 80 gr hollow point boat tail bullet. Perfect keyholes! Then is when I remembered that for a 22 caliber, light weight bullets need a loose > say 9 twists to be stable. Heavy bullets like the 80 gr need a tight twist 8 or faster. Later I noticed on the box of Berger bullets a note 1:8 minimum twist. So, I have to remember what I am going to call a “rule of Thumb”; Heavy is tight light is loose!
So, now I ask how does this apply to other calibers, for instance 30 caliber bullets are offered from 100 gr to 225 gr. How does the twist of the rifle, play a role in deciding which bullets are used in a particular rifle?
Perhaps some bullet company might, if necessary, develop a nomograph or other way of presentation to show, globally, applicable calibers and the relationship between Bullet weight (which determines how long it is, the real issue) and rifle twist.
In the back of my mind was the unrecoverable knowledge that twist is very important when considering the weight of the bullet used! I learned this many years ago on my Colt H Bar Match AR – 15 which has a 1:9 twist but unfortunately in remained forgotten.
Well, you can guess what happened I fired these 80 grain bullets out of the 40-X siting the rifle in. I shot a 5 round “group” and went down range to see the results. Well, they presented me with these beautiful profiles of a sierra 80 gr hollow point boat tail bullet. Perfect keyholes! Then is when I remembered that for a 22 caliber, light weight bullets need a loose > say 9 twists to be stable. Heavy bullets like the 80 gr need a tight twist 8 or faster. Later I noticed on the box of Berger bullets a note 1:8 minimum twist. So, I have to remember what I am going to call a “rule of Thumb”; Heavy is tight light is loose!
So, now I ask how does this apply to other calibers, for instance 30 caliber bullets are offered from 100 gr to 225 gr. How does the twist of the rifle, play a role in deciding which bullets are used in a particular rifle?
Perhaps some bullet company might, if necessary, develop a nomograph or other way of presentation to show, globally, applicable calibers and the relationship between Bullet weight (which determines how long it is, the real issue) and rifle twist.
