Desperatly seeking info

Living in Mass., it's impossible to buy lge. cap mags. for my mini. I purchased a no name 20rd. mag from an auction sight (1st. problem). I rcv'd. the mag today. It won't even fit into the stock. I am totally new to this. The mag I recvd. is @7/8 wide. My factory 5 rd @11/16. Did I recv. the wrong mag? I Have a ranch mini. Does this make a difference? I've gone thru the threads, but can't seem to find this info. Any responseswill be GREATLY APPRECIATED.

2b_prepared
:usa: