Not bead blast but blast with Aluminum Oxide. 60/80G
You can sand a lot of stuff but if it has a lot of angles it will bite you later.
For barrel pluggs I use an empty case in the chamber held in place with some rubber cement and foam ear plugs on the muzzle end
I have a question about prepping my ar for duracoat. Is it necessary to bead blast the upper and lower for the duracoat to stick? Where can I get barrel plugs around town to plug my new barrel for parkerizing?