Colt ar-15

[msorenso]

I have received as a gift an Ar-15 that was a family member.  I have a couple questions.  First how do I now what the barrel twist is and also if in can shoot military ammo or just 223.   Thanks
Also It is a colt ar-15

[Mikey]

To the best of my knowledge, the AR-15 is the civilian version of the M-16, lacking only the full auto capability.  It will shoot the 5.56x45mm/223 cartridge and may most likely favor the 55 gn bullet if it is an early model.  You should be able to contact Colt and give them the serial number and get the barrel twist if someone here can't help.  Mikey.

[msorenso]

Thank you Mikey

[Larry Gibson]

I have received as a gift an Ar-15 that was a family member.  I have a couple questions.  First how do I now what the barrel twist is and also if in can shoot military ammo or just 223.   Thanks
Also It is a colt ar-15

If it is of the M16 or M16A1 style it has a 1-12" twist and you should limit your choice of ammo (5.56 or .223 is fine regardless of the BS in several forums that they are different) to bullet weights of 55 gr or less. The M193 Ball ammo was the standard for this twist. If the Colt AR is of the M16A2 style and it is not new then it will most likely have a 1-7" twist. The Colt Competition ARs have 1-9" twists. Bullet weights of 80 gr or under are usable with the 1-7" twist. The M855 Ball with a 62 gr bullet is standard fodder for the M16A2 and M4s. The easy way to tell is if the AR is factory original and has the triangular forend it is a 1-12 twist, if a round forend it is a 1-7" twist. The twist can also be measured with a tight patch on a cleaning rod. Advise if you want to try this method.

Larry Gibson

[msorenso]

I noticed on the barrel it says Colt 5.56  then on the end it says 1/9.  I assume its 1 in 9 twist??

[dbo]

If your barrel is stamped 1/9, it's definitely a 1 in 9 twist.  My 1/9 AR shoots 75gr and 68-69gr loads fine (no key holing).  I'd suggest shooting a variety of loads to determine which one your rifle prefers.  That is the only definitive method of knowing for certain.