Ronbow,
When I purchased my Mini-30 5 years ago, I purchased 10 round magazines from U.S.A. Magazines. These were easily modified to 15 and 20 round capability when it became legal to own such again. These have functioned well in the rifle and have been capable of providing flawless feeding in all capacities. Odd that Ruger has not introduced their 10 round mag for sale, it is a honey, not protruding too far below the belly of the stock.