5.56x45mm-NATO

I don't think Norinco even makes a 5.56mm rifle in 1 in 12 twist. Even their old fugly CQ311's were 1 in 9.
 
do a little more research- the 1/12 stabilizes the 62 grain just fine-but that's right on the"outer limit" of the twist- you can use up to a 70 grain with a 1/10 -hence, the use of the 1/9 twist- it's for the use of tracers that the 1/7 twist was developed, - i've got a colt 1/7 in 20 inch and it doesn't like anything but the 68-70 grain slugs- there's a thing out there called the 'GREENHILL FORMULA" AS well as twust charts that tell you which bullet goes for which twist
 
Northern Pirate said:
I was under the impression that some AR-15 will not take 5.56 NATO, due higher chamber pressure.
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Get out from under that impression. :) Most new AR-15's are 5.56 due to export regulations from the USA. Also, most people want to fire 223 as it is more available and cheaper. The 556 is usually more expensive and hard to find.
 
Northern Pirate said:
I was under the impression that some AR-15 will not take 5.56 NATO, due higher chamber pressure.
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You asked about stabilization and that was what I answered. I don't believe any AR15 being sold today in Canada cannot stabilize NATO ball ammunition.

As t-star said, 10" twist is considered optimum for the 62/63gn bullet, most ARs are either 9" or 7" rate of twist. I have more consistent results using 62gn ball with the 9" over the 7", many people report their 7" works well also. Either will stabilize the round. I don't think anyone is selling new 12" twist ARs, but, I have fired 62 ball with great success through mine, though I understand that some 12" twist barrels may begin to see groups open up, just not my experience, again like t-star said, you're at the outer limits of 62gn with the 1/12.

As far as pressure, I have yet to hear of anyone with any brand of AR15 being sold in Canada today having pressure issues with 556NATO ammunition. If someone is/has, please speak up.
 
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