Fun (obscure) fact. Factory 10 round rotary mags rattle when they are loaded to capacity if you shake them. Below 8 rounds they make no noise. 9 rattles a bit, and topped off it sounds like something is loose in there.
Its handy for an Appleseed/RR when you are laying on your shooting mat and forget which has 10 and which only has 2.
Ruger makes factory single shot, 5 shot, standard 10 shot in black and clear, 15 rd, 25 rd and 50 round factory mags. They are by far the most dependable. Ruger also produces a 3 pack of the 10rd mags now which works out cheaper than buying them seperatly. I also use the alangator adapters so I can carry three 10 mags at a time with me. they are great for steel plate matches.