You could probably, using a true thermal fit, hold the barrel extension to the receiver with Duct TapeThe barrel nut threads and the front face take the load.

The locking lugs hold the bolt to the extension. Firing force is exerted there.
Yes, I understand that the tension of the threads holds the extension tight to the front face of the nose.
Which many (but not all) lap flat and square.
Half the threaded nose doesn't even touch the extension.
The handguard takes the bending moment and places it at the nose and front of the receiver.
The combined assembly, with a heavy walled receiver, or a custom receiver, of Nut (internal or external) ,extension, has more support than a thin walled receiver for heavy barrel(4 to 5 pounds) applications.
Last edited: