[QUOTE=dedhed;22905052]FD-M310 says 47.5mm chainline

Shimano's specs list it as "47.5/50mm" chainline. Probably since these level FDs are typically used with cranksets that uses square taper or Octalink V2 BB. Shimano list some these cranksets with 47.5 or 50 chainlines depending on which of the 2 recommended BB length used.