If a bill of sale is a problem or, as someone suggested, they demand to see my bill of sale, then there is always a legal transfer via a 4473 through a dealer. That way, both parties are covered.
What I do not understand is why people attack or denigrate those who do want a bill of sale or a transfer. We, as firearm owners, are already under attack and I wonder why we are not able to respect each other over this.
There are actual court cases where a person executed a bill of sale. Buyer used the gun in a crime. Bill of sale came into play that proved sale of the gun to a felon. Which turned the seller into a felon since he sold the gun to a felon.