Abstract: Employee #1 and a coworker, both carpenters, were constructing wooden wall panels for apartment buildings. At approximately 1:45 p.m. on June 24, 1993, the two carpenters were working across from each other on an outside cut truck (assembly area) on a wall panel 11 ft 5 in. long and 8 ft wide with cross studs every 16 in. Some wall panels vary in size. Duofast nail guns, with 110 lb pressure, 130 psig max, were used to nail the wall panels together. The coworker was nailing the cross studs and Employee #1 was bent over to nail the header onto the jack of the wall panel. The coworker shot a nail in the plate that should have gone into the cross stud but, instead, came out through the top of the plate, nicking the cross stud. The nail flew across the work area and struck Employee #1 in the middle of his chest. A 4 in. incision allowed the doctors to remove the nail and eleven staples were used to close the incision. Employee #1 suffered no internal injuries. The nail gun had passed inspection that morning and immediately following the incident. The safety clip was in place and working properly. The nail possibly was fired into the wood at a bad angle, or when the nail went into the first piece of wood it possibly hit a knot or something that caused it to exit the top. The nail was not bent and, apparently, came straight through the wood.