I am a retired cop from NC. I have struggled with this same topic my entire career. Here, what a depart does with "evidence guns" is subject to anyone in authority making the decision. Our SO has sold evidence guns or traded them as long as I can remember. My PD was a different story. We were selling them or trading them to FFL's when I started. Over the years it changed with the wind. The chief, major, city manager, city attorney, any judge, the governor, SBI Director..... could change it at any time. Our admin decided to destroy all of them. At one time we were the local ATF firearms test agency. We test fired and entered bullets and chasing into the ballistics computer. We asked if we could keep certain magazines like the S&W's we a mag safety. Our attorney said absolutely not. Long winded again but that's the whole 9 yards.