I have one of these for my AR, and was wondering if Colt made a 20 or 30 round magazine for them. It came with a 10 rounder, which is a pain in the a**. You just start to have fun, then need to stop and reload.Would a Ceiner 30 round mag work, or should I try to find a few more 10 rounders?

AFAIK only the Ciener ever had hi-cap mags, and they're not compatible with any other kits.  Maybe you could modify them to work, but at the current prices it'd be an expensive experiment.

one thing I like about the design of the Colt adaptor is that you can unscrew the magazine case to get to the basically stock-looking mag inside- it looks like it was originally designed for one of their bolt action .22 rifles- if one simply lifts out the original ten round mag it would be relatively simple to modify it for greater capacity. The top of the mag is critical since it has the correct angle for chambering and has the ejecter built onto it. Perhaps extend it using some other cheap and readily available surplus units, cutting a hole in the mag adaptor to allow the extension to fit thru. Anybody tried this yet? Oh course a huge drum magazine would be even nicer...
Chet

Bought a second Colt 22 mag last week for my winter project experiment. A longer mag body should not be hard, but getting the spring tension and length right may be the hard part. It may just turn into a 10rnd backup mag..