x2 on zippy13's post.
I sold a 40 S&W handgun many years back. I later found 8 boxes of reloaded ammo I must of stored away at some point. Not knowing the law, I put an ad in the local paper to sell it. The first call I got was from the BATF. (no "E" yet at that time) They asked for my FFL#, of which I didn't have.
Given the two choices of where the situation might go, I chose to remove the ad at their recomendation. We later shot up the ammo at our cabin when a visitor brought his 40 along.
Good luck.
E.