re: Best fitting to refill green propane bottles.

By putting the small bottles in the freezer first there is a chance to "overfill" them. No "fiery" explosion like you see on TV, but the walls of the bottles may distort and expand out. This happened to several of mine and I threw them out (although they still worked). I would weigh them as filling to ensure they don't overfill especially if you put the green bottles in the freezer. Don't just hook them up and not pay attention.