AR-15 with a 1:9 twist

[KnotRight]

A couple of my ARs have a 1:9 twist with a 16" barrel. I can hit steel @ 300 yards with a 55 grn FMJ bullet. Anybody shooting a 223 with this twist rate?
What would be the heaviest bullet you would try to shoot?
I would like to try the 400 and 500 yard steel but think the 55 grn is too lite.

 

[bigfelipe]

1-9 is good up to about 62gr I'm told... then you want a faster twist. 1-8 is the median, 1-7 is the mil standard with and accurate floor of around 62gr but I use 55gr all day long with acceptable accuracy in my 1-7 twist barrels. 55gr will reach 4-500yds easily if you're just ringing steel. Accuracy will depend on the ammo and the barrel....

 

[JBoyette]

No heaver then 69grn .With 1/9 and 69grn smk add 4 moa of left past 500yds

 

[AR10ShooterinNC]

I have an RRA AR-15 with a 20" barrel, 1-9 twist. I shoot 69gr Nosler Custom Comps. At a 100 yards I can shoot .5 MOA and can keep them all on a 12" plate at 600 yards, once I get the wind call right.

 

[NKD]

Just watched a video where a dude uses a 1-9 and shoots 77 & 75 more accurately than his 1-7. And, oddly, his 1-7 shoots 55's better than the 1-9!! Opposite of common wisdom.
So, I'd say it is worth some testing.

 

[JBoyette]

Just watched a video where a dude uses a 1-9 and shoots 77 & 75 more accurately than his 1-7. And, oddly, his 1-7 shoots 55's better than the 1-9!! Opposite of common wisdom.
So, I'd say it is worth some testing.

I would bet you both rifles are 1/8. 99% of people never mesure the twist rate they just go with what is engraved.

I know a manufacturer of barrwl blanks that does pull 1/8 then engraves what ever the customer requests.

 

[Mightyox04]

I would bet you both rifles are 1/8. 99% of people never mesure the twist rate they just go with what is engraved.

I know a manufacturer of barrwl blanks that does pull 1/8 then engraves what ever the customer requests.

That's terrible if its true.

 

[Slacker]

I would bet you both rifles are 1/8. 99% of people never mesure the twist rate they just go with what is engraved.

I know a manufacturer of barrwl blanks that does pull 1/8 then engraves what ever the customer requests.

Lol! I can hear the cleaning rods getting pulled out!!
Best post up the utube method of counting twists per inch!

And then there is Gain twist....

 

[NKD]

I would bet you both rifles are 1/8. 99% of people never mesure the twist rate they just go with what is engraved.

I know a manufacturer of barrwl blanks that does pull 1/8 then engraves what ever the customer requests.

Indeed, that is often true with measuring.

Can you let us know the barrel maker so we can make sure to not spend out money there?

 

[JBoyette]

Indeed, that is often true with measuring.

Can you let us know the barrel maker so we can make sure to not spend out money there?

They are out of business now tooling moved so its pointless at this point. But alot of people never think to measure. Other factors that people do not think of twist is directly related to the bullet weight you plan on shooting AND OAL of rifling, not OAL of the barrel, two different measurements. As a example:

The .308win bolt guns I build are 1:8 or 1:7 twist because I have found you need two full rotations of the bullet before it exits the barrel to have a high level of precision. Lets do a simple math situation.

20" OAL barrel and 1:10 twist. = less then 2 rotations in rifling.

why?

Barrel OAL is measured from the closed bolt and includes chamber measurements.