Aero Precision barrel nut too tight

[robtmc]

Wanted to replace my old Midwest handguard that had to be loctite bonded to stop slippping.

Mid-70's DPMS LR308 receiver.  Got an Aero S-ONE FF handguard with barrel nut claimed to be "ar308" compatible.  DPMS is mentioned.

No way, started a thread or so then needed a wrench to got any further.  NOT cross threaded.

The Midwest nut goes on by hand.  Aero claimed lack of commonality with the 308 and claimed nothing they could do.

I have trouble believing the upper receiver threads are that mismatched.  I know Armalite is different but should not have even started if that was the case?

Aero's description for just the barrel nut does state only for their threaded upper receivers.

[sketch]

Pic's would help.  I can't say a mid 70s dpms is compatible with newer areo parts? Is there a chance that the barrel nut was cross threaded before? 

*Just for shits make sure you use factory torqued specks.  *

[robtmc]

Bought the upper in 2007, not 70's.

Not cross threaded, can get it on with some effort, not cross threaded, the Midwest nut goes on by hand still.

[robtmc]

I did find an old post from a guy had the same oversized thread problem.  Tolerance stacking.

Funny because the Midwest barrel nut fits fine with just a touch of drag in a few spots.

Tried a JP HG years ago with the tight thread problem and sent it back.  Had forgotten that.