In the wake of the tragic shooting in Parkland, Fla., Dick’s Sporting Goods, Walmart and several other major retailers have announced changes in the way they’re going to sell firearms. Many are raising the minimum age of buyers allowed to purchase firearms to 21 years old. Dick’s has also decided not to sell assault-style rifles and high-capacity magazines. But here’s the thing: as big as these two chains are, they (and the other two large chains Cabela’s and Bass Pro Shops) represent less than five percent of gun store retailers in the country.