Mikhail Kalashnikov, inventor of the iconic and ubiquitous AK-47, outwardly expressed pride in his rifle before his death last month, even though its being used by terrorists saddened him. However, in a letter sent to Russian Orthodox Patriarch Kirill I of Moscow, the late engineer felt spiritual pain about his inventions capacity to kill, and wondered if he was, in the end, responsible for the deaths it caused. My spiritual pain is unbearable.