That would make it, once again, bigger than an M3. The Bessa isn't a rangefinder, so it's totally moot as a counterexample. Horseshoes and hand grenades.
My statement stands: a 120 rangefinder almost certainly can't be smaller than an M3. The claim that someone switched from an M3 to a 120 rangefinder because it was smaller is delusional and potentially way confusing to people reading this thread in a year or five or ten.
I own and use both, I've got no horse in this race except the containment of misinformation.