M40 A1: What can it do, what can go with it ? What I do know is that: Current M40 can be converted to 357 sig with a barrel change M40 and M357 mags are interchangable if not the same IGB and Steyr sell conversion barrels There are stocks available but no 16" barrels BT and and an Israeli company offer recoil solutions BT sells other cool stuff There are 10 and 12 mags availalble What else ?... This is the section that should be nesrly empty: What I don't know is: What calibre barrels drop in to the M40 frame without mods What converts caibre without cutting ? Can I convert to 9x18 or 9x19 or .22 rimfire at all ? What aftermarket mags work with M40 ? Which mags work with mods ? What Mods ? Does anybody do mods ? Tell us what we don't know please.