Republican A.G. Push Visa, Mastercard, AmEx Not To Track Gun Sales Watch Video A group of Republican attorneys general are pushing the major payment networks — Visa, Mastercard and American Express — to drop their plans to start tracking sales at gun stores, arguing the plans could infringe on consumer privacy and push legal gun sales out of the mainstream financial network. The letter comes more than a week after the payment networks said they would adopt the International Organization for Standardization''s new merchant code for sales at gun stores. The merchant code would categorize sales at gun stores not unlike how payment networks categorize sales at airlines, restaurants, and department stores. SEE MORE: Major Credit Card Companies Will Soon Categorize Gun Store Purchases In their letter, the AGs threaten to use all legal tools at their disposal to stop the payment networks from tracking gun sales. "Categorizing the constitutionally protected right to purchase firearms unfairly singles out law-abiding merchants and consumers alike," the letter said.