I had a Rossi coachgun. I can’t remember the barrel length but it might have been 20 inches or maybe 18.
I liked it but those Luparas carried by the bodyguards looked like expensive shotguns.
One of the best scenes, where the tavern owner’s anger vanishes when young Corleone offers to marry his daughter. The bodyguard translating hesitates at the word “sposa”.
I’ve freeze framed trying to identify the make of the shotguns, but hammerguns are still the standard shotgun in Italy. Pumps & autoloaders? No, signore.