working on my own at that time. >> but leskowski remembered using a dental casting material called mikrosil in a case where he needed to see tool marks in a piece of metal. so, he decided to try some of that by putting it down the barrel of the gun. >> it consists of two parts, a silicone rubber base and then a catalyst or hardener. and basically it comes in two tubes. so, when one squeezes a certain amount of rubber material out and then a corresponding amount of hardener out, you mix the two together, and in this particular case, we injected the caste into the barrel and let it harden. >> it took 15 minutes for the mikrosil to solidify inside the gun. when it hardened, leskowski