I'm lookng for an interior shot of the M590 showing placement of the Mini-14 and any reenforcements they may have done to lock the shooting parts in place in the fiberglass shells.
Most people have the rubber or solid cast versions and not the live fire version or shell so that going to be a tough picture to get I would think. Good luck though.
unless it didnt happen, the last of those rifles was cut up as it was costing more to keep them "working" then it was to rent them. I may be wrong but I believe they dont exist anymore.