Is there such a thing as a chart or series of charts that will give the correct rifling twist for various calibers and bullet weights?
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Is there such a thing as a chart or series of charts that will give the correct rifling twist for various calibers and bullet weights?
There is a formula, based on the Length (bearing surface) of the bullet.
Proper Twist:
150* x caliber diameter in inches x (cal diameter/bullet length)
*For velocities over 3000fps use 170, and under 2500 use 130
Proper Bullet Length:
150 x cal diameter x (cal diameter/twist in inches)
Bear in mind that this is a general guideline. It's usually pretty good, but I can't tell you how many times I have seen a barrel stabilize a bullet that is much too long or too short by the book. Neither rifles nor bullets can read. ;)
The bottom line is you have to actually shoot it to get that particular barrel's opinion. Most recently, I advised a shooter that his .223 with a 1/10 twist would probably not stabilize a 70gr bullet. Usually they keyhole and pattern like a shotgun. He proceeded to shoot a one hole group with the rifle at 100yds with his handloads. His comment was "I'd read that, too. Don't tell my rifle, OK?"
generally the longer [heavier] your bullet, the faster your twist rate.
the greenhill formula above is pretty close though.
remember it is just a guidline,and you can go over or under what it says.
mainly cause, guns are just like that. some will some won't.
Thanks guys.
I was given this ling by someone on another forum which is very good.
http://www.riflebarrels.com/products...wist_rates.htm
Your link doesn't work.:cry:
If you look at the tables at the end of each section of "Cartridges of the World" they list the twist rates for each cartridge.
Good morning
The NRA Fact Book has a section on ballistics,stability, rotation... does get real DEEP... simple easy and I enjoy the book.
Mike in Peru
Quote:
Originally Posted by duncaninfrance
Here's a few threads you can follow:
http://www.riflebarrels.com/products...wist_rates.htm
http://www.nfa.ca/content/view/129/197/
http://www.montanabulletworks.com/wst_page11.html
Mike