While you are on the site, in your browser find and click "Add to Home Screen" A CGN beaver app icon will then be created to your phone that is directly link to the site.
Note: This feature may not be available in some browsers.
FWIW I figured a way to hold the receiver in the lathe chuck without risking any damage to it.
I 3D printed an internal / external jig that slides over the back of the receiver and fits tightly. The exterior of the jig is shaped to allow a 4-jaw chuck to grab it. The base of the jig has a large round extrusion to fit inside the chuck bore so the whole thing will be concentric to the lathe bore without having to screw around.
The receiver jig worked really well. Then I ran the muzzle in a live centre, which keeps the barrel perfectly aligned with the bore and leaves ample room to turn and thread the muzzle. Easy peasy.