Visa's recent statement regarding the new Gun Store MCC code was maybe a little deceptive. They claim that this won't allow insight into line item data of a transaction.
I think Visa is conveniently failing to mention "Level 3 line item data". From the interwebs:
"Level 3 processing and sending line item detail is an advanced method of processing commercial, purchasing, fleet and government credit cards. It involves sending additional fields of data through the processing network. This is up to 12 fields of additional information, much like you would find on an invoice. With the additional data a business can monitor what kind of purchases are made on a company card, where, how much etc. It can also include restrictions, limiting the types of businesses an employee can make purchases. Visa and MasterCard created special rates to support Level 3 data by reducing the transaction cost when level 3 processing data is included with the transaction. This often lowers the transaction cost by up to 40%."
Many smaller merchants are just automatically opted in on this, and they don't even know it. If they are using a turnkey POS system, this is often built right in. For larger merchants (Walmart), they will mostly likely be voluntarily participating in Level 3 data because it lowers their processing rates.
Clayton E. Cramer
Gun Free Zone
The War on Guns
The View From Out West