[ZED SLED]

Originally Posted by blake-b

1:9 means the bullet spins 1 revolution every 9" thus making it a slower twist than a 1:8 or 1:7. Early M16s were 1:14.

The twist rate could affect accuracy because the heavier bullet may not be spinning fast enough to stabilize so it yaws going through the air and can keyhole a target (hit it sideways or otherwise not directly point first). Typically, a heavier bullet needs a faster twist rate.

Stands to reason. Thanks for the explanation.

[Frank237]

It's not only HEAVIER bullets that may not stabilize in a slow twist....But LONGER slugs too....like all metal X bullets. And some cup and core match slugs with very long, tapered bodies with a large hollow area between the core and bullet tip.

[Norm Peterson]

Is there some upper end to how fast a bullet should be spinning, and wouldn't there be some dependency on muzzle velocity?

Unless I've missed something really important, 1 in 9 for a .223 Remington sounds like well over 200,000 rpm.


Norm

[Tenring]

Pretty good read on twist rates:

http://www.gunsandammo.com/ammo/pair...st-rates-ammo/

[Norm Peterson]

Wish I could have read more of the comments. Damn site insisted on streaming some video ads and kept hanging up with some "long running script". I gave up after three tries to get past about the middle of the first comment.


Norm

[Norm Peterson]

Thanks, Ten. Damned if I'll ever understand why the link in the emailed notice worked better than the link in the earlier post

Turned out that only two out of 13 comments were worth reading (but that was enough). Saved it to a Word file so I can read it at my leisure without the page crashing . . . again.


Norm

[Frank237]

Originally Posted by Norm Peterson

Is there some upper end to how fast a bullet should be spinning, and wouldn't there be some dependency on muzzle velocity?

Unless I've missed something really important, 1 in 9 for a .223 Remington sounds like well over 200,000 rpm.


Norm

Stability, especially at LR ,is of course dependent on velocity. When conditions are just right, you can see the air disruption, or "trace" of the slug as it passes through the air. Follow it out to the point the slug goes unstable and you can actually see it veer off. It's very cool to see.

Lots of shooters will build a rifle to shoot heavy/long slugs then want to shoot the very light slugs for that caliber as well. Many will say the bullet is "over stabilized" whatever that means? I have a 6mm with a 1 in 8" twist and it will shoot as light as 80 gr bullets at well in excess of 3200 fps and they ALL seem to make it to the paper.

BUT...to muddy the water...I have also seen very light, very frangible varmint bullets in my .220 Swift, with a 1 in 9" HART barrel....NOT make it to the target! Then again...very thinly jacketed slugs. A slight bit of out of balance and they are dust.

Go to the Berger bullet site and they have a chart with the twist rates suggested for their various bullets.

[Frank237]

http://www.bergerbullets.com/twist-rate-calculator/

Berger bullet twist calculator.

[7WSM]

Originally Posted by bpang1234

School me on this please?

Like others have said, it's to stabilize the heavier/longer bearing length bullets. The US mil had to move to a 1:7 twist to stabilize the 62gr SS109 bullets. If one was to shoot nothing but 55gr and lower grain bullets, the 1:9 would be fine. Why would one restrict oneself in the bullets they can shoot out of a gun. 1:8 and 1:7 twist barrels are so common nowadays, I just don't see any reason for any company to bring any AR15 or any .223/5.56gun out with a 1:9 twist.

[ZED SLED]

So, sounds like it boils to down as to whether you intend to shoot zombies at 50 yds or the man bun off of a hipster's head at 200

[sherob]

Originally Posted by ZED SLED

So, sounds like it boils to down as to whether you intend to shoot zombies at 50 yds or the man bun off of a hipster's head at 200

... or a He-Hive.

[7WSM]

Everyone is out there having kids and building up their cars, I'm here collecting stamps.

My MK12 ModH

[SS6310]

I’m partial to Colt, I carry a Night Defender 45

[Tenring]

Originally Posted by SS6310

I’m partial to Colt, I carry a Night Defender 45

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