Interesting choice by Dick's Sporting Goods today (https://pressroom.dicks.com/press-information/media-statements.aspx?camp=sns::20180227). Most of the headlines are focusing on the company's decision to stop selling AR-15s, along with their encouraging an AWB. Not much to see here, as it's totally up to them what they choose to sell.
More interesting to me is their choice to limit sales of firearms to persons 21 and up. I'm no lawyer, but I thought that the CRA limited a business's ability to deny service based on protected traits. In many states, age has been added to that list of protected traits. Obviously, this wouldn't apply to something limited by law (like alcohol sales age, or existing laws on gun sales), but if someone is legally of age to buy a rifle, can a business legally discriminate based on age and deny the sale?
Edit to add, the average age for mass shooters is 34, with the preponderance being white males. Just imagine if their discrimination criteria was "we won't sell guns to whites, males, or people between 30 and 39."