So today at LGS looking thru misc SW mags and found a flushfit 6rd to fit my 4513tsw. They also had 6rd curved baseplate 45 mags. Didn't pu because I wasnt sure they would seat correctly. Came home and took curved base off 7rd mags,and put it on 6rd and it fit perfect in gun. Looks odd tho. what are the 6 rd curved origiallly for??