4513 mags
4513 TSW with cut out and six round mags (two styles of basepad) is early version; later versions are essentially 7 rd 4516's. So:
Mags from 457, 4513, 4516 and 4506 will work in early 4513; in fact, any S&W metal frame .45 mag will work in it except the mag for the CS 45. (Actually it probably would, if you have an early cut out style 4513; vice versa will not work I'm told) Suggest stay away from mags with yellow followers.
I own CS 45, 457, 4513, 16,66,06 and 745. Mags for all of the above at the very least seem plentiful on Gunbroker, though may be priced a little high, or current retail; some deals show up there from time to time, I personally resist paying $40 for anything that is not NIB, though would go that far if they were more rare than I experience them to be. Try Ky Imports? CDNN wholesale? As good as any on price.
I like the 4506 mags with the black follower.
There are really only two styles of mag not specific to the 4513 (8rd 4506 and 7 rd 4516) basically, though in different revisions (stainless follower and base, stainless base and orange follower, black plastic base with yellow follower, black plastic base and black or orange follower (8 rd 4506, 4566, 6/745 mag) Current iteration is black & Black.
There are two styles of 7 rd. 4516 mag; one with black follower and basepad, and those with yellow followers which seem to be stamped as being specific to the early 4516 and -1.
457 and 4516 mags are interchangeable.
Have fun.
TF
