A friend of mine picked up this semi-auto carbine, made in Argentina, for cheap. It had been neglected, and had a thin layer of rust on the barrel, the magazine and both front and rear sights are missing, and the charging handle is a home-made replacement. I cleaned it up for him, and there's actually some hope for it, if I can find a magazine. I see Raul had helped another member here locate a magazine in Argentina a few years ago. While I don't expect that lightning to strike twice, I wonder if anyone here has found another magazine that works or can be adapted to work in these rifles. From what pictures I've found, it appears to be a nearly straight walled mag, retained by a heel release, and looks to have been available in 10 and 20 round capacities (I'm guessing, based on the pics. )
If anyone has one of these magazines, I would greatly appreciate some pictures, with the dimensions of the mag body, so I can try to locate a suitable substitute, if I can't find an original.
UPDATE 06/13/13 - I took a chance, and answered my own question. I found an eBay vendor selling American Arms Mini-Max 22LR magazines. They appeared to be the same design as the pictures of the M-21 factory mags I'd found online, and there are several online posts associating American Arms and Mahely. Since the seller had a return policy, I took a chance and bought two of them. They arrived yesterday - very sturdy, unused steel mags, with removable baseplates. Both fit the rifle perfectly, and feed dummy rounds without a problem. I'll get these to the range this weekend for live testing, but I think we've got a winner here.