"Most nights in Afghanistan, I wielded an M4 carbine...My rifle was very similar to the AR-15-style semiautomatic weapon used to kill students, teachers and a coach I knew at Marjory Stoneman Douglas High School in Parkland, Fla., where I once lived...I cannot support the primary weapon I used to defend our people being used to kill children I swore to defend...The AR-15 is an excellent platform for recreational shooters to learn to be outstanding marksmen. Unfortunately, it is also an excellent platform for those who wish to kill the innocent."