How do you know if the gun you bought is brand new? I know that certain guns will include 2 casings to show that it was shot. But besides that Im seeing alot of black on the inside of my gun more than just the normal oil. Is there a way to check either by serial number or just from not so new but not so used look of wear? MY dealer is pretty reputable and I dont see why they would sell me a used gun. But again how do I know if a person traded it after a round at the gun range or if it was a floor sample, or rep. sample?