Twist rate, can someone give me a crash course?

thewhitebuffalo83 · Jun 3, 2012

Hi guys, I am curious about twist rate. I just picked up my Mega stripped lower a couple days ago and I was set on building a AR pistol but now I am thinking maybe not. I am however thinking a pistol caliber carbine would be really cool or maybe just another AR15 variant idk. I see often posted 1/9,1/8,1/7.... I understand that different twist rates are better for different weight bullets or different cartridges can someone school me here. I am considering a 9mm carbine or just another AR15 variant? I already have a carbine length AR and a Long range AR. What do I need to know in general for either a 5.56 twist rate and 9mm twist rate.

I know 9mm has a really limited range but I was thinking of losing my sub2000. I just don't like it as much as I thought I would, maybe I will warm up to it down the road.

Thanks in advance for any help.

iamme · Jun 4, 2012

Yep- search!

http://www.northwestfirearms.com/rifle-shotgun-discussion/91363-ar15-barrel.html
http://www.northwestfirearms.com/rifle-shotgun-discussion/67925-question.html

There were lots more as well.

Old Hick · Jun 4, 2012

Is this what you're looking for?

Stay Safe.

bruzer · Jun 4, 2012

Cool charts.
Mike

thewhitebuffalo83 · Jun 4, 2012

Thanks for the chart, it looks like a 1 and 8 is best overall for most bullet weights. Thanks again.

Nwcid · Jun 5, 2012

Those charts are just for 5.56. 9mm will be different.

Twist is based on bullet length not weight. Most people use weight because longer bullets are usually heavier.

thewhitebuffalo83 · Jun 5, 2012

Nwcid said:
Those charts are just for 5.56. 9mm will be different.

Twist is based on bullet length not weight. Most people use weight because longer bullets are usually heavier.

Thanks I knew the chart was just for 5.56, and I looked all over online for some 9mm twist rate info and it looks like I am screwed all I can really find is different opinions and also I now realize that there might be a handful of twist rates for the 9mm but I am only able to find 1 and 10 in stock and only at a few places.

Thanks again for the help guys.