I have three Midwestern rifles, all made here in Illinois, that were made without buttplates. Two are by Samuel Smith, who started out in Fayette County, Pennsylvania, then worked in Ohio, before coming to Astoria, Illinois just before 1850. There is nothing crude about either of them, both are well fitted and have nice architecture. One is incise-carved and has a bit of engraving. The other has a beautiful hand-forged iron trigger guard. Both are maple fullstocks. I have two other rifles by Smith, that have brass buttplates. One has a full patchbox. I think that what the customer wanted to pay, determined what was or wasn't on these rifles.
The third one is by John Daniel, a gunsmith/blacksmith who's family came to Mason County, Illinois from Tennessee during the 1830's, when he was still a boy. That one is a very graceful, iron mounted, walnut fullstock, which does have a heel plate and a toe plate.
I also owned an Iowa-made "chunk gun" for a number of years, that was made without a buttplate. It weighed 25 lbs. and was a fullstock, stocked in red elm. The maker was Michael Zerbe, who had apprenticed in Pennsylvania before moving to Cedar County, Iowa, during the 1850's.