https://www.primaryarms.com/Plinker_.../pt30rd001.htm

YMMV some folks don't care for these, this site is live inventory and ships quickly if interested... no personal experience with the mags.

I like these mags. I have one, and it seems to work fine, other than not catching the bolt after the last shot. My LGS had some, wanted to pick up a second one. Kicking myself now.

These Plinker mags seem to be showing up at different places.
I've read about them here,found them in stock at 2 LGS's and at Cabela's here in Indiana.
I did pick up 2 of them but haven't had the time to try them out yet. I'm really hoping I'm one of the people that have good luck with them.