LITTLE ROCK, Ark. (AP) — The gunmen in two of the nation’s most recent mass shootings legally bought the semi-automatic rifles they used in their massacres after they turned 18. That’s prompting Congress and some governors and state lawmakers to revisit the question of whether to raise the minimum age for purchasing such high-powered weapons. Only six states require someone to be at least 21 years old to buy rifles and shotguns. Advocates argue that such a limit might have prevented the elementary school shooting in Uvalde, Texas, that left 19 children and two teachers dead and the racially motivated supermarket attack in Buffalo, New York, that killed 10.