How do I use a Blunderbuss?

I buy the Blunderbuss. I equip it on a character in the Camp. I go to the Town Cryer. I get into a match and see the Item Bag on the character action wheel. I select the Blunderbuss and nothing.

Im going to try taking off any ranged weapons and see if using the Blunderbuss gives me a ranged attack.
 
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