The one I have is marked "BARCALO - BUFFALO U.S.A. // PAT. OCT. 4, 1938 - No. 111,564" so there are some marking variations.
I'm in the process of working up patent 2,230,376 for DATAMP. It is essentially the same tool, but as a regular patent has more information about the intended function of all the features.
Google that patent & read the specifications -- in particular the passage about the "carbonated beverage can opener" function. ;-)