1. The Ruger factory 5-round magazine should work flawlessly. Third-party magazines for the Mini-14 tend to be problematic; I have some that work well and some that don't. If there is any particular manufacturer whose products are consistently better than others, I'm not aware of it. Trial and error.
2. Be very careful of the bolt hold-open function on the Mini-14; it is not secure. Try the following: after making certain that the chamber is unloaded, the magazine well empty, and the bolt held open, strike the butt plate smartly on the floor and see what happens.
3. The Mini-14 gas mechanism is advanced over some of its predecessors in that, every time the rifle cycles, the gas mechanism is exposed to the atmosphere. On the one hand, this makes for some soot emitting from under the handguard; on the other hand, the mechanism tends to be somewhat self-cleaning. That said, disassemble the rifle from time to time and clean both the nipple attached to the gas block and the chamber into which it inserts (front of the operating rod) thoroughly.
4. If you are going to reload for your Ruger, do enough research to understand that semi-auto rifles are sensitive not only to peak chamber pressure, but also to propellant burn rate (which governs where in time peak pressure occurs). Add to that the fact that, all other things equal, you'd like something that burns comparatively cleanly, and you conclude that semi-auto rifles are a bit fussy. After some experimentation, my favorite powder is Win748, but others may differ.
5. Likewise, if you're going to reload for it, be aware that the Mini-14 is no less (and no more) susceptible of slam fire than an M-1. While, in theory, the pin is restrained from primer contact unless the bolt is rotated into battery, there is an emphasis to be placed on being certain that primers are seated sub flush. Also, do not single-load the Mini-14 by sliding a round into the chamber and then dropping the bolt; always slip the round under the lips of a magazine and let it feed in the usual way.
6. Mini-14's are not particularly accurate. The barrel is both thin walled and flippy in contour, and this coupled with the necessary contact with the stock, handguard, and gas mechanism all sum to a rifle that will never be a tack driver. On the other hand, for what it was designed to do, the Mini-14 is a fine device.
7. Adjusting the factory Mini-14 rear sight can be a pain (both figuratively and literally). Ruger will sell you a sight adjusting tool for short money. It is worth it.
