I have not had any issues with Pro Mag. I know they have a bad rap for AR mags but I haven't seen any issues on the Mini-14. I've only fired a little over 100 rounds though, so I've hardly thoroughly tested them yet. Ruger mags are a safer bet, but they don't sell the nickel-plated ones anymore. When did they stop? I haven't seen them since the 80's. I like my nickel-plated mags for the consummate alternative to black rifles. Diversity. I got the 20-round Pro Mag for $20, stripped them, cleaned, found no need to de-burr, dry-lubed, and installed Wolff extra-power follower springs ($5 in 3-packs). I bought all from Midway when the mags were on clearance. They're a couple bucks more at the moment.
Ruger magazines can cost 75% more than Pro Mag and even 40% more than Pro Mag plus Wolff springs. I bought Pro Mag only to get nickel, but the price also helps when you're buying an armload of them. Of course, the savings are worthless if they won't function. That hasn't been my experience so far, but they do have a warranty.