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Posted: 2/10/2006 4:47:25 AM EDT
I have an early A1 upper reciever with a teardrop FA and no shell deflector. I want to build this as an early A1, just after the slabside upper...

What was the barrel twist rate at that time.....1/12 or 1/9?

When did the rate change to 1/9? How long did it last?

The A2 has a 1/7 rate, correct?

Couldn't find the answers in the archives or the AR important threads listing....

Thanks
Link Posted: 2/10/2006 4:52:40 AM EDT
IIRC, 12 twist for A1, 7 twist came next, 9 twist came last. Charles.
Link Posted: 2/10/2006 4:56:55 AM EDT
Your A1 should be 1 in 12. The military never went to the 1 in 9 but went to 1 in 7 in the mid eighties when they switched to the heavier ball/longer tracer round. 1 in 9 is a civilian compromise because it's a better all a round twist for both light and heavey bullets, up to about 70 grains or so. 1 in 7 is better if you're going to use the relatively new 75 - 80 grain loads. By the way, Maadi's rock!!!
Link Posted: 2/10/2006 5:42:56 AM EDT

Originally Posted By Battlecloth:
Your A1 should be 1 in 12. The military never went to the 1 in 9 but went to 1 in 7 in the mid eighties when they switched to the heavier ball/longer tracer round. 1 in 9 is a civilian compromise because it's a better all a round twist for both light and heavey bullets, up to about 70 grains or so. 1 in 7 is better if you're going to use the relatively new 75 - 80 grain loads. By the way, Maadi's rock!!!



Thanks for the info on the AR. I have a line on a 1/12 barrel, govt profile................

Yeah MAADI's do rock. I have two... a CAI, and an INTRAC.
Link Posted: 2/10/2006 6:00:04 AM EDT

Originally Posted By archer2:

Originally Posted By Battlecloth:
Your A1 should be 1 in 12. The military never went to the 1 in 9 but went to 1 in 7 in the mid eighties when they switched to the heavier ball/longer tracer round. 1 in 9 is a civilian compromise because it's a better all a round twist for both light and heavey bullets, up to about 70 grains or so. 1 in 7 is better if you're going to use the relatively new 75 - 80 grain loads. By the way, Maadi's rock!!!



Thanks for the info on the AR. I have a line on a 1/12 barrel, govt profile................

Yeah MAADI's do rock. I have two... a CAI, and an INTRAC.



Well what do you know! My Intrac is on the top and my CAI is on the bottom.

Link Posted: 2/10/2006 6:29:24 AM EDT
Mine.
INTRAC on top, CAI on the bottom

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