My Mini 30 was bought slightly-used in March '08. Here are the facts.
It has only used newer ('06-'08) Russian-made Wolf and Monarch.
The only good aftermarket mags for my rifle are recent 10-rounders built by Promag (have blued and stainless).
Out of about 600 rounds in these new Promags, have had about 4 rounds mis-feed (almost as good as with some AKs). Not bad.
Anyway, since I started using this rifle in March '08, again using only newer Russian ammo, there have been no more than 10 ftfs (only with the first primer strikes) in over 1100 rounds fired. You can order a stronger firing pin from Wolff or maybe Brownells. But my rifle probably has the original spring.
Some people seem to get confused about newer Russian-made x39 ammo, and lump it into one group of foreign.....
1) None of this Russian is corrosive. Being called 'dirty' does not equate to corrosive.
2) None of this Russian is (mil.) surplus, as it was manufactured to be exported for the commercial markets.
Yugo x39 is often both surplus and corrosive, along with old Chinese, but not fairly recent Russian-made.
Unless you are going to fight either the Taliban, Al Qaeda or the gentlemen of Hezbollah or North Koreans, you will probably be satisfied with the Mini 30.
Lots of guys on gun websites seem to be expecting their house or Ponderosa to be overrun by a raving pack of criminals, or Red Chinese soldiers any minute now...