advice for installing barrel assembly?

[CHS]

My military tech manual is an older version (1970's ?) and doesn't mention the three-torque method. Also, it says to use 25 ft/lbs torque.

The 25ft/lbs should be the MINIMUM torque, since you need to torque more if the gas-tube scallops are not lined up.

[ar15barrels]

ic. what does torquing it and loosening it then torquing it do?

It burnishes the threads so that they come to torque more consistently.
You can feel the threads mating the first couple times you do it.
By the 3rd torquing, they are sliding smoother and therefore the torque is more consistent.

If you don't have time to do a job right, you should not be doing it in the first place.

[ar15barrels]

Wow, and that was due to an improperly-mated barrel to upper?!

No, that's from a high primer or an improperly installed firing pin.

Properly assembled AR's with safely assembled ammo just don't have out-of-battery issues.
The bolt carrier and bolt interaction won't allow the firing pin to be forward until the bolt lugs are FULLY engaged.

[unamused]

so no word on the receiver mount from ebay?

[Swatter911]

I would also recommend using the proper grease the -23 calls for. The exact spec mixture is found in AeroShell 33MS, or you can get Valvoline Durablend Moly grease as a substitute. Neither contains graphite.