Draco had seen the same thing in Hermione's face; the horror that he had used a gun on the soldiers, and the Penduduk Di Luar member. Somehow it had been worse to her than a curse that had a similar effect. Draco suspected in her case it was an instinctive reaction, retained from her childhood amongst Muggles. If the rest of the Order didn't like the idea of using guns it would probably mostly be thanks to an aversion to change, and a general uneasiness with Muggle technology.