12/01 probably means the 12th frame in 2001. 58 must be the sizing and B57 is whatever Sergio drank that day. looking at it i first thought... 57 boom... "Sergio thats an 58er! ah okay - stamps a B in front of it like it would mean something different and places fhe proper 58er stamp as well..."
And fhis would sound to be a believable tale... but..
on another Masciaghi built machine the same pattern appears..


51B54???? Second could be length? Anyone?