My primary Mag-10 was made in 1976, I bought it in 1984. It worked well with lead shot but the early steel loads were problematic. I replaced the original springs with a kit from Wolff in '86 and again around 1998 and it has been trouble free since.
A few of the parts interchange between the Mag-10 and the SP10 but usually need some fitting. Many more don't and are difficult to find so when I ran into one for cheap I bought it for parts. I haven't had to raid it for parts yet as I don't use the 10 ga as much as I used to but it is there if needed.
