I was convicted 20yrs ago?
Not if you have access to the firearms. It is illegal for you to possess firearms or ammo, even if you do not own the firearms. Just having control over them, which I imagine you do since you are likely handing them to potential buyers, could get you in trouble. You are better off avoiding it. If you did not serve any time you should look into whether your felony can be reduced to a misdemeanor, thereby restoring your firearm rights.
Michel & Associates, PC
All my comments here are intended for general legal purposes. None of my comments here establish an attorney-client relationship with anyone. None of my comments should be relied on in taking legal action without first consulting an attorney.