The inventor of the Kalashnikov assault rifle apparently wrote to the head of the Russian Orthodox Church before he died expressing fears he was morally responsible for the people it killed.
Mikhail Kalashnikov, who died last month aged 94, wrote a long emotional letter to Patriarch Kirill in May 2012, church officials say.
He said he was suffering "spiritual pain" over the many deaths it caused.
Kalashnikov had previously refused to accept responsibility for those killed.