I acquired internal tooth lock washers to bolt down the ground wire to the aluminum maglite body, but I soon recognized that the curvature of the aluminum does not allow for flush contact of a washer or nut. Attachment 1 shows a 4-40 screw and nut relative to the maglite body. 

I am continuing to search for the best way to get electrical contact, given these constraints and the issues with soldering in the last ELOG.