You've got a really nice collectors piece! Ethan Allen started making under hammer PISTOLS, in Grafton, Mass in 1834 and he made and stamped his name on quite a few of them, but I've not yet seen any under hammer rifles made by him (if he made any, they are really rare). Without any marking on your gun or any further substantiation of the the maker, I'd personally be reluctant to ascribe it to him. Several other makers produced similar guns to yours. Indeed, this particular gun looks somewhat like under hammers made in the New Hampshire- Vermont border area , such as those made by David Hilliard in Cornish, NH. But without actual hands-on inspection, this is only a guess