I've never had this issue. My friend would crash his game sometimes with his The Vanity(I think that's right FWC HC from vendor). But he dismantled it and never had a problem with any other weapons with the perk. My other friend uses his Hung Jury all day. No problems there. Try another gun with firefly see if that works. My favorite is my Hand of Judgment, a scout with explosive rounds and firefly! Boom!