By Zach Despart The Texas Tribune UVALDE — Once they saw a torrent of bullets tear through a classroom wall and metal door, the first police officers in the hallway of Robb Elementary School concluded they were outgunned. And that they could die.The gunman had an AR-15, a rifle design used by U.S. soldiers in every conflict since Vietnam. Its bullets flew toward the officers at three times the speed of sound and could have pierced their body armor like a hole punch through paper. They grazed two officers in the head, and the group retreated.Uvalde Police Department Sgt. Daniel ...