Walmart has won praise from gun control activists in the United States for restricting sales of gun ammunition in its stores.The company announced on Tuesday it plans to end the sale of some kinds of ammunition. Walmart has also asked people not to openly carry guns in its stores.Gun control advocates welcomed the announcement. But whether the changes will result in fewer weapons on U.S. streets remains an open question.The announcement follows similar steps by other gun sellers after public pressure to restrict gun and ammunition sales.In March, Dick's Sporting Goods said it would stop selling guns and ammunition at 125 of its more than 700 stores. In addition, other businesses, such as Starbucks, Target, Wendy's and most recently Kroger, have asked customers not to openly carry guns in their stores.Supporters of stronger gun laws say Walmart will have a huge influence on the gun law debate because it is the nation's largest retailer. Gun control advocates are demanding that U.S. lawmakers and large companies take action.Igor Volsky is the founder of the group Guns Down America. In a statement, he credited Walmart for joining the "majority of Americans who know that we have too many guns in our country and they are too easy to get." The statement said that Walmart should make it clear to Congress that "it stands with Americans who are demanding real change."However, most gun sales come from thousands of individual gun dealers or gun shows, not big retail stores like Walmart. So it is not clear how much difference the changes will make. About half of Walmart's close to 5,000 U.S. stores sells guns. That represents only around two percent of all guns nationwide.Walmart said it will stop selling ammunition for handguns, and for two kinds of short-barrel rifle, after the supplies currently in stores are gone. That will reduce the company's market share of ammunition from around 20 percent to between six and nine percent. That information comes from the company's chief, Doug McMillon.Walmart also plans to discontinue handgun sales in Alaska. It stopped selling handguns in the 1990s in every state but Alaska. The latest move marks its complete exit from that business so that the company can direct its attention on hunting rifles and ammunition only.The company is also asking customers not to openly carry guns at its Walmart and Sam's Club stores unless they are police officers. But Walmart added that it does not plan to change its policy for customers with permits to carry concealed weapons. The company said it will be adding signs in stores to inform customers of the changes.The announcement comes just days after a gunman shot and killed seven people in Odessa, Texas. That follows two other shootings last month, one of them at a Walmart store.Last month, a gunman entered a Walmart in El Paso, Texas, and killed 22 people. It was the deadliest shooting in Walmart's history.Nine people died in a second unrelated shooting that same day, in Dayton, Ohio. A few days before that, two Walmart workers were killed by another worker at a store in Southaven, Mississippi.In 2015, the company stopped selling assault rifles like the AR-rifles used in several mass shootings.A letter from company head Doug McMillon said, "In a complex situation lacking a simple solution, we are trying to take steps to reduce the risk that events like these will happen again."The National Rifle Association, or NRA, criticized Walmart on Twitter after Tuesday's announcement.NRA's Twitter post said it was "shameful" to see Walmart surrender to the pressure of "anti-gun elites." The tweet also warned that the company would lose customers to other gun sale shops.Gun control supporters have asked Walmart to stop supporting politicians who accept money from the NRA. And I'm John Russell.