Is it marked Mowrey? Mowry? (I think some of the later guns had this spelling.) I can recall maybe fifteen years ago a fellow showing me a rifle and it might have been in the fast twist like that. When I said, "Oh, that's a Mowrey, from Olney, Texas, right?", he got kind of insulted and told me that it was made by someone else. Something about the action being more sophisticated or superior, etc. Might be this is one of those?
Actually, there was a .54 Mowrey-styled gun at a recent gun show here in Northern Virginia. Had no markings whatsoever. It carried the heavy buttplate like the one pictured. The old Mowrey's had a s/n in the toe plate but this did not. Was going to ask if it was a Deer Creek kit gun but figured the seller wouldn't know as it was with a bunch of smokeless guns.