The number of retailers raising the minimum age of firearm sales is up to 4. 

Via Statesman Journal:

More retailers across the nation are reacting to calls for gun reform by stopping firearm sales to anyone younger than 21.

Eugene-based Bi-Mart was the latest to join the growing list of stores making the policy shift, which already includes Fred Meyer, Walmart and Dick's Sporting Goods.

"Ours is a very political business," said Doug Raaf, owner of Guncrafters in Salem, which sells rifles and shotguns to 18-year-olds and hand guns to 21-year-olds.

"We're not going to change (the age) until they change the law," Raaf said. "When the feds tell us to do it, we'll do it."

He said the larger retailers are making the change for publicity's sake...

... Gun advocates have taken exception to the new sales bans. Richard Thomson, a grassroots director with the Firearms Policy Coalition, said in a statement the stores "are alienating millions of their customers and going out of their way to take troubling political positions."

Read more here.