Marines? I enlisted in the Army ten years later in 1967. I got to fire the M14 a lot, but no pistols and nothing automatic. I was even on KP the day everyone else got to go out and throw a grenade, grrrrrrrrr!
We had to throw those too. Both the old pineapple and the newer round wire jobs. You had to be able to throw practice grenades far enough to qualify to throw a real one. We had people fail that, though I don't know how, I was the smallest guy in the company at 5'5 and 107 lbs and I qualified.
The platoon leader had fun with me, had me fire a grenade from an M1, from the shoulder, that caused my whole right shoulder to turn black and blue.
I forgot to answer your question. Not Marines, Army. I enlisted in the OK National Guard when I was 16. The unit was actually AA so I got to fire Quad 50s at summer camp, nearly deaf today. I was active there 2 years then went RA served 3 years got out messed around a while and joined the Navy on a lark, just to see the world.