I'm kinda late but, the large revolver helps for doing combo, you can put the minimum and with the perk of mana (the one that it cost 15 mana and tells you the next if is blank or bullet) you can keep pulling the triger until a bullet shows, then you do a roll and start again, if you get the one that add +2 of money each time is a blank space then you can get very rich in a short time.
That's what i atleast did
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(sorry for late response) for what i think, you have to spin the charger (where you put the bullets, idk how is the name in english), after that there are new items in the store until you do it again.
said that i can go back to my previous message, a larger gun can make you produce money for a longer time with the combo i said, so you don't have to worry about losing a item you want from the store.
hope this helps ya in the game