So far a lot of subjective comment ref the Breda 12.7mm in game. A browse through this web site might add some real data to the debate:
http://www.geocities.com/capecanaver...n/fgun-in.html
Also in the jpg below from Flying Guns of WWII (Pg 331) by the same authors*whose web site I refer above. The Gun Power column is perhaps the most relevant in this debate. Of all the 12.7mm guns in this table the Breda has the lowest gun Power. In relative terms thats what we see in game imo.
*Anthony G Williams & Dr Emmanuel Gustin , arguably the subject matter experts in this field.