Robert,
Since you are so damned concerned about "spec" .. care to comment on the issue with a gentlemen's Remington/AAC SD whatever rifle listed here :
http://www.ar15.com/forums/topic.html?b=6&f=20&t=337480
Sounds to me like Remington f*cked up the threads here and told the guy to pound sand.
I'm waiting for your reply.