I just cant see why you would want a 30 rd mag when your only firing semi auto. I have a Thompson w/ a 30 rnd stick and its a pain in the ***. I can see why the U.S. Gov. went with a 20 rd. stick in WWII. The SkS really wasnt designed for it(30 rd stick). If it flips your switch I guess go for it. But I think they stick out like a sore thumb.