I am changing the handguard from free float A2 GI type to CMP extension tube type. This is on a WOA NM upper. The CMP tube is from RRA.

The barrel nut torks to the minimum 30# with the gas tube hole just a little bit beyond lining up.
The 80# maximum tork does not reach the next hole. In other words I can't find the hole at all between 30# and 80#
Can I tork to just under 30#?
Or are there shims available?

Tighten and loosen it three times...this will seat the threads and should get you to the next gas hole. This is standard military doctrine.

That happened to me on a 16" mid length FSB build. Did the tighten and loosen thing several times and finally it settled in on the high side. Always use aeroshell moly grease!

quote:

Originally posted by MikeinNC:
Tighten and loosen it three times...this will seat the threads and should get you to the next gas hole. This is standard military doctrine.

Did that.
I did use an Anti seize

They also make shims if the tighten loosen tighten doesn't work.

If that doesn’t work, I’d torque the fuck out of it, before even considering backing off...you can stretch aluminum threads...it’s just an upper.

I'm in the other camp. I shot an AR for years torqued to zero pounds. Barrel nut was so loose it rocked back and forth, the gas tube was the only thing holding it on. Zero malfunctions, probably the most accurate AR I've ever owned.

All is well

Got shims and the recommended grease.

With a .007 shim, the gas tube lines up perfectly at 40#

Now I just gotta line up the three rails. Receiver, handguard, gas block.
I'm thinking span the receiver and handguard rails with a scope and two rings to tighten the lock ring. Then I guess just visual on the gas block. As best I can tell the gas block port is lined up. Should I put blue locktite on the handguard lock?

This is a RRA pix of what it looks like. Only the upper is a NM WOA now with the RRA handguard. The WOA barrel is unthreaded