The 357 rim is about 1mm bigger than 9mm. I will buy a lever action in ...
No it does not depend on the bolt head. 357 mag headspaces off the rim (9mm headspaces off the case front edge). Without the rim, how do you get the round in the chamber correctly? Your lifter can only feed rounds within a range of lengths, and 9mm is much shorter than 357mag. How do you even lift the round?