No true. Vendor accounts have coding that tells the card company what kind of store is being patronized. It is conceivable that a dedicated gun shop could be coded as such and could be blocked.
A good example of this in action is VISA debit cards tied to health savings accounts. The transaction will decline if you try to use it somewhere like Best Buy, etc.
In the example you explain, then the ENTIRE GUN SHOP would be banned from all credit card sales wouldn’t it? As a matter of fact ALL gun related businesses in the United States would be banned by Chase for ALL credit card purchases.
Now, use some common sense.
Banks have buried in the merchant fine print all sorts of exorbitant fees. Almost always if there is a charge back the bank fees and penalties will far exceed the amount being reversed. All a merchant has to do ONCE is be on the losing end of a ‘charge back’ extortion and the merchant will STOP using that payment method forward.
There is no ‘innocent until proven guilty’ in the eyes of banking institution.