I was setting up at the range today when two guys caught my attention trying to clear a jam in a G36. The round had truly jammed attempting to move into battery. The round was partially in the barrell before it jammed. We were finally able to clear the jam and low and behold they were shooting lead round reloads. A few minutes later they called me over and asked if I knew how to break down a Glock (the meant field strip). I field stripped the G36, looked into the barrell and found that none of the rifling was visible - they were all filled with lead! I could not believe that 1) he was shooting lead in the Glock factory barrell and 2) wasn't cleaning it with a lead solvent. On top of it all, this was the guy's carry gun.