An original Powder Springs Georgia 10 was my first Class III selective fire. When I bought it (1976 or so), I had the luxury of being allocated 1000 rounds per month for "Proficiency Training". It was, undoubtedly, the most "fun" gun I've ever owned. I had to sell it when I went overseas (couldn't see paying to store it in a safe deposit box).
FWIW, the M3 mags work perfectly with just a touch of filing.
It taught me the true meaning of "Why waltz when you can rock 'n roll"