I would shy away from the steel cased Berdan primed ammo. I'm absolutely positive there are people that have fired thousands of rounds of it with no issues but there are enough reports of broken firing pins that I wouldn't use it. My reasoning is this, if you break a firing pin in that rifle you will have to send it back to Ruger to be fixed. I'm not sure I'd want to be without my rifle that long if it could be avoided. Also Ruger will remove any modifications you may have done to your rifle and set it back to factory specs, this means if you've had a trigger job done they will replace all those parts and you will have to have it done again. Also Ruger may not cover the repair under warranty if they know that you were using the steel case Russian ammo. The firing pins in the Mini rifles must be fit to the bolt so Ruger will not sell them they are a factory only part. The only aftermarket firing pins that I know of are the Glend Arms pins which are reportedly not as good as the original firing pins and must still be fit to the bolt of the rifle which for most people will require a gunsmith. Go over to perfectunion forums and do a search for broken firing pin in the Mini-30. Then again maybe I'm just a little over protective of my rifles.