"Private sales do not require a background check and so a felon or lunatic might use that avenue to illegally obtain a gun. The merit I see in the antis argument is that this is an avenue that should be closed."
Expanding on that "logic," a felon or lunatic might well break into the home of a gunowner and steal a gun, thus obtaining it illegally.
So, logic would follow that the anti argument for banning and confiscation of all privately held guns in this country has merit, and ownership is an avenue that should be closed.
Congratulations. You're on the slippery slope and gaining speed.