There is an outfit out of Australia who makes a version that takes Ruger mags and/or modified AR mags. Can't get him to ship one to me in Canada, but he apparently has a significant Canadian customer who gets 10 or so at a time ... so I assume some importer here somewhere is bringing them in. Appreciate if anyone knows who to post a contact number.
h ttp://www.sbactiongunsmithing.com.au/gallery.html
I have seen one on a rifle in Calgary (rather, I saw Ruger mags used in a Rem 700SA .223), which I believe came from the same outfit - worked quite well.