I just traveled from the US and packed 8oz of tobacco and 200 tubes along with my machine that packs them. I declared the 8 oz tobacco. If I would have pre-rolled them I would have declared 200 cigs. I believe you can bring in up to 16 oz of tobacco or 400 cigs (2 cartons) without paying duty. I ran out of tubes while I was in JA and brought about a 1/2 pack and a few oz of tobacco back into the US which I didn't declare. I did mention it at US customs. There were no questions asked either way.
