How do make 10/3X subgun mags (PPSH, Suomi, etc.)

[RaceDay]

So does anybody have a relatively easy and proven way of converting the 35-36 round mags into 10 rd. I know Allied Armament sold 10 rd mags with their PPSH. I know some people have 10 rd M31's. Are you guys using mag blocks or rivets or something else?

[Someguy925]

Allied Armament actually cut stick mags down to 10 rounds.