yes, I made the "sten" mag for my first smg, and was it ever a pita. Sten mags have no "spring' in the metal, just a double layer of sheet steel. Bill Holme's first book, the smg, shows you how to do it, but it's a big waste of time and effort. I also rifled the first smg barrel, until I realized that I could get 6 of the 3" long barrels, out of a $35 Uzi barrel, with just a chambering reamer and a die for threading the barrel-chunks. 