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Twist and bullet weight

This is a discussion on Twist and bullet weight within the Ammunition forums, part of the M14 M1A Forum category; Originally Posted by Puccini It's not only the weight of the bullet that determines accuracy in any given twist. It's also the shape of the ...


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Old March 8th, 2017, 02:05 PM   #16
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Quote:
Originally Posted by Puccini View Post
It's not only the weight of the bullet that determines accuracy in any given twist. It's also the shape of the bullet.

The more metal that contacts the bore/twist the more accurate.

Thats why 6.5x55 bullets are generally more accurate. They have a long shape and more contact with the bore.
Well... yes and no.

It really has nothing to do with how much of the projectile touches the bore but where it touches the bore, the "wheelbase, so to speak.

If you look at the projectiles below, they really only contact the bore in two places, the rotating band just above the boat-tail and at the bourelette at the start of the ogive section. The portion of the body between these two areas is relieved so as not to touch the bore.



An extreme case:


The longer the distance between the two furthest bore contact rings are, the less likely the projectile will be cocked off-parallel to the bore centerline. Also, the smaller the magnitude of the maximum crookedness.


Last edited by lysander; March 8th, 2017 at 02:29 PM.
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Old March 8th, 2017, 02:17 PM   #17
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If you really wanted a long 'wheelbase" and a really long ogive, this is also a possibility, this design does not have a cylindrical section, just an ogive stuck on a boat-tail.



Yes, someone actually makes these: (the picture is kind'a big)

http://www.yugoimport.com/sites/default/files/1_15.jpg

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Old March 8th, 2017, 02:43 PM   #18
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twist rate

Much good info here...thanks Forum! this is what I was looking for, food for thought, things to consider. It will definitely play into my load development schemes no matter what I am developing!

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