At my last Front Sight Shotgun class there was a girl next to me and she shot a 12 ga 870 for the entire 4 days and after figuring out how to mount the gun and keep her cheek on the comb of the stock she didn't even have any marks on her. She was all of 5' tall and maybe 95 lbs, but she rocked right along with the guys and I know she could deal with a problem effectively after that class.
I saw her fire a couple of rounds of High Based Buckshot which she didn't really like and showed her the Low Recoil stuff which she did like,,, and bought more of during lunch.
The good thing about small women and shotguns is they generally roll with the punches pretty well so they don't absorb as much recoil as big guys do.
I admire any woman who chooses to get trained with firearms, but am especially fond of Shotgun Girls, most have bigger cajones than the guys they show up with..
Randy