Quote Originally Posted by AR-10 View Post
Regardless of the receiver extension type, the torque is 40 foot lbs.

If you're looking in a -23&P manual, that is a typo.

It's 35-39 ft. lbs. for a rifle receiver extension and 40 ft. lbs. for a carbine.

Edited to add: I really, really don't like 4-position tubes. I had one on my Colt and found myself actually needing more positions, exactly in the spot where Colt left them out. I replaced it with a 6-position LMT tube and I've been happy ever since.
I agree with you on the 4-position tubes.