Guy showed up at the range last week with a new Ciener conversion. Got the chance to compare mags with my DPMS. Good news: The Ciener and the DPMS put the mag body in the same place (NOT like the M261). Bad news: The Ciener mag of course doesn't have the built-in ejector that the DPMS needs. I didn't get a chance to put his mag in my gun or see if it'll feed. BUT! It looks like some adaptation might be possible. Of course you will have to silver-solder on an ejector thingie. Ciener is supposedly sitting on a warehouse full of the hi-cap mag bodies. This is worth looking into further.

Notice I have not PROMISED that this will work, just that it seems at this time as though there might be a possibility of something....

EDIT: Well, nuts! I thought I was posting this in the Rimfire forum! Is it possible for a mod to move it where it belongs, please? Thanks!