All sales made through a dealer must have a background check done first. That is a federal law. Some states, Colorado included, require a background check if the sale is made at a gun show. Many states do not require a background check for a face-to-face sale between legal age residents of the same state. Colorado does not require any paperwork at all for a face-to-face sale so there is no paper trail to trace a gun to you. I don’t know if the dealer paperwork records the model and S/N of a gun. Maybe a FFL holder on here would know.
Yes, it is tragic that I lost every gun that had dealer paperwork when my canoe turned over on that camping trip. That is the reason I can’t turn them in. That is my story and I’m sticking to it. /s