I believe that would still meet the classic definition of entrapment. Randy Weaver got off on that basis when he sawed off a shotgun to less than 18 inches. The line of thinking goes that the "criminal" would not have done it unless a government agent hadn't encouraged them to commit the crime.

I can envision situations where I would sell, or even give, a firearm to a known felon. Example, a slightly built woman convicted of embezzlement 30 years ago who now has an ex that says he is going to kill her. If it turned out that she was actually a government agent and I was the jury for someone that made that sale I'd be advocating the prosecutor be whipped in the courthouse parking lot and left hanging on the post for a couple of days without food and water.