I am trying to think of a reason for a 16" barrel & especially on a single shot rifle. A bolt/lever gun of the same length would have a 12" barrel, never mind the legal part, so are you hunting in an area so thick that a
"brush" lever rifle could not be used at all. The Handi Rifle in 45-70 is shorter than a lever action 30-30 now. If you feel that you need to cut the
tube, I would do as Mac stated & cut to 18". You saw the picture of the Encore in 18". Who would need a shorter gun than that?