Following the Parkland massacre and a fresh wave of gun reform activism, big retailers are slowly starting to pull out of some parts of the gun business. Dick’s Sporting Goods, Walmart, Kroger, and L.L. Bean all announced this week they would no longer sell guns to anyone under the age of 21.In addition, Dick’s will stop selling assault-style rifles and high-capacity magazines, while Walmart will stop selling items resembling assault-style rifles, such as air guns.Support for gun control is surging, even if the chances of broad national legislation still look slim: A recent Quinnipiac poll found that 66 percent of voters and 50 percent of gun owners support stricter gun control. But it’s hard to know whether these moves by retailers will have much of an effect on gun sales. Walmart had stopped selling assault-style rifles in 2015, citing a lack of consumer demand, and Dick’s stopped selling assault-style rifles in a majority of its locations following the 2012 Sandy Hook massacre.Without a national registry, we don’t know exactly how many assault-style rifles are out there, though the NRA estimates there are between 8.5 million and 15 million assault rifles in the U.S. An estimated 12 percent of assault-style rifles sold are purchased at large retailers, according to a report prepared for a gun industry trade group.While ending sales at big-box stores will create good will from their pro-gun reform customers, that may be all it does.