Earlier this month Visa, Mastercard and American Express announced a change in the way the companies categorize purchases from gun stores. This week, 24 Attorneys General from Republican states are urging the payment processors to rethink that move.

Credit card companies use merchant category codes to classify all purchases. Until recently, items bought at gun stores were listed as “general merchandise.” After some lobbying by Democratic lawmakers and gun control activists, the three credit companies adopted the International Organization for Standardization’s new merchant code for gun sales.

Gun reform advocates said the new codes could better help track surges in gun sales, which they argue could be a prelude to a mass shooting. Critics said the new merchant codes could infringe on consumer privacy, and push legal gun sales out of mainstream financial networks.

The Republican Attorneys General said in a letter to the companies “categorizing the constitutionally protected right to purchase firearms unfairly singles out law-abiding merchants and consumers alike.”

Critics of the new merchant codes also pointed out they would do a poor job of tracking potential red flags. For instance, the sale of a gun safe worth thousands of dollars would get the same classification as someone spending thousands of dollars on ammunition.

The Chief Financial Officer of Florida, Jimmy Patronis, said if the state legislature convenes and the new merchant codes are still being used, he will work with lawmakers to punish any business that he said is targeting the right to bear arms.

The Associated Press contributed to this report.