OK. I'm going to attempt to educate you all. I know...
So credit cards like visa are companies. Imagine your favorite cash back rewards card. It's likely an agreement with a bank or credit union and one of those credit card companies.
Those companies own the cards. But they DO NOT OWN THE NETWORKS THOSE TRANSACTIONS ARE RUN ON. Those networks. Call them cables if you will. Those are owned by different companies.
Those different companies get to make up their own rules and do. Then banks get to decide to use which one of those lines. Bank of America uses the one that prohibits any firearm related transactions to be processed accross their lines. Many others do as well.
Previously firearm related transactions were coded as sporting goods. And bank of America would love to setup your firearm business to process credit cards through them. And they would. Humm profits.
Eventually the network would find out they were firearm related charges and tell bank of America to close your account. And they would. And bank of America would get to freeze your funds based on their terms of service. That's right. It was predatory for a reason. Many many firearm related business got their accounts shut down or frozen because of this.
It's not visa who is out to get you. It's the backend providers who do the transfers. Visa is complying with them. And in some ways it might be better for firearm related businesses.
These same backend providers also have rules regarding sex related, vape or smoking related, etc accounts and transactions. It's a game and its been around for a long while.
I'd wager there are a pile of gun companies currently at jeopardy because they trusted their bankers.
Here is one such backend. First Data
en.m.wikipedia.org