So, after years of waiting for Armalite to actually make some flat top AR-10B uppers, I got tired of waiting, and cut mine off with a hack saw.
From there it went to my mill, using a custom upper holding mandrel.
Cut it down far enough to add a length of universal picatinny rail, that I machined to fit down over the upper.
And after drilling & tapping a bunch of little bitty threaded holes, I now have a flat top that matches the rail height of my other upper/barrel.
Was all the time worth it ?
Not if Armalite would have ever made some uppers.......But they never did.
Still have to LocTite all the screws.
The refinishing will come after I do a FAL charge handle conversion.
Have the handle, and just ordered the T-slot cutter.
Just need to order in some W1 tool steel to make the track that the handle will slide in.