TWISTS
CAN SOMEONE PLEASE EXPLAIN WHAT A 1IN 9, OR 1 IN 7 TWIST IS AND WHAT IS BEST AND WHY? THANKS WAYNE.
IF IT AIN'T BROKE DON'T FIX IT!
IF IT AIN'T BROKE DON'T FIX IT!
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Twist is how many inches it takes for a full rotation of any given bullet in the barrel.The 'Best" is determined by each caliber and bullet weight.It is a science unto itself, and most manufacturers have determined a basic standard that is applicable to any given cartridge.
Love them Pre-64's!!!!-Bob0 -
QUOTE:1IN 9, OR 1 IN 7 TWIST IS AND WHAT IS BEST AND WHY?
what caliber?
yep its me ,same one for 4 years now0 -
I'm not a techie, but I have a 1x9 twist in my AR-15....that's one complete turn every nine inches. That's also so I can best shoot a medium to heavy grain bullet.
The twist rate affects the bullet flight tremendously and there are many internet sites to read about the subject. Look into sniper sites, twist ratio for rifle barrels or type in any line you think has your answer. DPMS will also talk you through it on the phone...
The guys who REALLY know their stuff should follow soon!!
"They blink an eye or draw a breath before they pull a trigger. I won't!" J.B. Books0 -
Have to know a lot more than what you've given us. Heck I have a rifle that is 1 in 66 ... pretty darn accurate, but it makes an awful lot of smoke[:D]
give us caliber and weight of bullet(s) you want to work with.
If you only have time to do two things so-so, or one thing well ... do the one thing!0 -
Bullet length,not weight,is what depends upon a specific twist rate.
The faster the twist rate(lesser distance in inches,for the bullet to complete a revolution,as it travels down the bore),the longer the projectile that can be stabilized in a given diameter.
With the rates given,my assumption is that it is a .224" centerfire in question. The 1-7" rate will stabilize a longer bullet,than the 1-9" will.
The 1-9" will handle most bullets to 70grains or so,their exact make-up,the determining factor(length). The 1-7" allows more flexibility,in that it will handle even longer projectiles. Some are hesitant to employ "too much" twist,but I tend to err on the side of caution. Meaning rather than try to hit the precise twist rate upon the head,I like some cushion,in case new options present themselves down the road. Cushion comes via a faster twist rate(lesser numerical designation).
I've shot 40's in various 1-7" AR's,with much satisfaction and the door was open to more mainstream projectiles,typically encountered within that platform.
Long way of saying,a 1-7" twist .224" barrel will capably handle a wider spectrum of bullet weights(lengths),than a 1-9",1-10" etc. If you can ascertain which projectiles are your focal point,you can begin to fine tune a specific twist rate.
When in doubt,I believe it prudent to employ some added twist. Keyholes are over rated(grin).........................0 -
Big stick,..e-mail me.
why chase the game when the bullet can get em from here?....
Got Balistics?0 -
This is likely very old news to most, but the Greenhill formula from 1879,lets you calculate optimum rifling twist for a given bullet length, or optimum bullet length for a given twist rate. Twist rates are:-150 X (calibre in inches squared, divided by bullet length in inches)e.g. .308 bullet, 1.35" long = 1 turn in 10.54" is optimum. For bullet length:- 150 X (calibre in inches squared, divided by twist rate in inches)e.g. .308 bullet with a 1 in 8" twist barrel = 1.77" is optimum bullet length. 0 -
Jeerome589-
Here are a few websites to help you wade through this for yourself. I think they will be very helpful.
1.) You have not identified the firearm/caliber in your query, but I think I have a good idea what it is. Anyway, this website will address several different calibers/twist-rates.
http://www.shilen.com/calibers.htm
2.) This website covers projectile stability with a very scientific but understandable approach.
http://www.nennstiel-ruprecht.de/bullfly/stab.htm
3.) I think this might be interesting reading for you also since it discusses some issues regarding the .223. It looks to be an extensive yet casual discussion of an opiniative nature.
http://www.sportingrifles.com/stabilisation_problems.htm
Best Regards0 -
JustC,
Email sent...............0 -
Just wondering ..... is it the total bullet length that matters or is it that part that contacts the rifling? In other words, is the optimum bullet length the same if the bullet is a spitzer or a flat point? It seems there weren't many pointed rifle bullets around in 1879. 0
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