Homemade AR Upper Vise Block

I loaned my upper vise block to my son a while back. He is in Virginia and I am in Florida. Rather than him shipping it, or buying another one, I am thinking about making my own.

This is my concept; router out a ½” by ½” slot down the length of a 7”-8” long piece of 2” x 4” (1-1/2” x 3-1/2” ) . The takedown lugs would fit into the slot. Then I could clamp it in a vise with another piece of 2” x 4” on the top Picatinny rail.

Anybody else tried anything like this, or sees any risk? This is a quick cross-section sketch:


I am changing out a handguard, so I need to swap the barrel nut. Since the barrel is already seated, I am thinking of leaving the BCG and Charging Handle in the upper to possibly provide some structural support. Comments?


So, to complete this thread, the routered 2 x 4 holding fixture worked out! It would have been nice to have a third hand holding both boards and the upper in place while snugging up the vise, but I persevered:

Please forgive my messy garage!

The new 14" handguard installed with the old 10" for comparison. Part of the gas block sat outside the 10" handguard.

And the new handguard came with a nifty new tool to put in the used once box …