I am so angry at myself. Fortunately I had followed at least 2 of the three rules. There was no serious damage. I came home from college for the summer, and wanted to inspect my guns after not seeing them for so long. I thought I had removed every cartridge from the cylinder last night, saw them on the nightstand. I decided to go downstairs and do some dry firing practice. I pointed in a safe direction down towards a phone socket on the bottom of the wall facing the backyard the the greenbelt behind it. Rather than using dedicated dry firing blanks, I stupidly decided to use a pen to catch the hammer to prevent damage to the pin. There was one cartridge left inside, and the hammer still connected with enough force to set off the cartridge, destroying the socket. The gold dot fragmented and it did not pass through the wall. I couldnt hear anything and just remember feeling stunned that a NID actually happened to me. I thought I'd been careful, I looked at the cylinder and didn't notice the cartridge in there. I am so ashamed and disgusted with myself right, and thinking about my lack of responsibility. I think it might be best to sell off my guns.