If you have a trained eye some LE trade ins can be great. Departments buy firearms and a certain amount of spares. If you are good you can find the spares which will almost be brand new.
I havent been lucky enough to find spares....but they are out there.
I won't argue that at all. For instance..... the mini 14's at a state prison. The stuff in a tower is NEVER shot, the ones used to qualify with 1,000's of times.
If I'm buying used anything I always put a bullet in the muzzle, yes it's a cheap go / no go gauge but it's always worked for me.