Hope I don't offend anyone with this post. I listed an interesting black powder era Cape Gun on gunbroker yesterday evening: https://www.gunbroker.com/item/838769537
My picture file sizes are too large to show here . Lots of pictures shown with the listing. Pristine bores. Sweet old gun.
Anyone with a guess on the rifle caliber could help me out. It came with a slightly shortened .45/70 case in the chamber that seems to be slightly necked down. I have a picture of it with the listing. I will attempt to get a chamber casting shortly. Shotgun barrel is .16 ga 2.5".