We were issued 1200s when I was in the Army, and they had a host of issues that civilian guns probably would never see, but they were there, and I'd avoid them, if it were me. I've owned several 870s, S&W 3000s (think Japanese 870, with improvements), and Ithaca 37s, and a Mossberg or two.
I like the now defunct S&W 3000s best (made by Howa), followed by the 870s. Ithacas are nice, but kick more than the other two brands. I sincerely doubt I'll ever own another Mossberg, but I'd rather have one of them than the 1300.
