10-20-2011, 08:19 PM
I used to think the 9/16 thread was crazy too, but now I know why Bill chose it. At the time, there weren't a lot of alternate calibers for the AR, as most of the AR10's were target barrels. Armalite decided to be different, and went with a 5/8x24 thread pattern so nobody could use any other muzzle devices other than from them on their carbines and 20" guns with threads. The 9/16 actually pre-dates them since it was used on the British L1A1, since you couldn't go larger than 9/16" on those barrel profiles.
As the popularity of AR10's surged, and everybody started making them, they went with a 5/8x24" pattern to ride in on the Armalite coat tails. Suppressor-makers followed suit, and 5/8x24 became more and more popular, to the point that everyone associates it with the standard for .308 pipes. Kinda funny history behind it all...
As the popularity of AR10's surged, and everybody started making them, they went with a 5/8x24" pattern to ride in on the Armalite coat tails. Suppressor-makers followed suit, and 5/8x24 became more and more popular, to the point that everyone associates it with the standard for .308 pipes. Kinda funny history behind it all...