I have deleted my reply and wish to belatedly apologize. I misinterpreted your post as advocating such laws (actually proposed bills that have virtually no chance of making it out of the House or Senate).
They wouldn't work anyway, and the people who introduced these bills are idiots. If you buy a gun using a credit card, chances are you're buying from a FFL. A background check has to be run and passed before you pay, so the government knows you bought one. And credit card companies don't know what you bought, only who you bought something from. Just because the merchant is, say, Guns Guns Guns Galore, it doesn't mean you bought a gun. It could have been ammo or accessories.
Caption this Meme
