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".

I looked at and it is a very nice looking rig, I'd hunt it.

I have a Sauer drilling (.16 ga x 8x57JR) that will be going deer hunting with me this year. Indiana passed a law allowing high power rifles a few years back and i have been using great, vintage European rifles to hunt with since. At 75, I hope I live long enough to work through them!!

I made the chamber cast this morning and the bore measures 0.447" or 11.38mm.
Anyone know of a source for bullets of that diameter?
Any help would be appreciated.
Thanks,
Jim Stanley

Found bullets for it, so that problem solved. Fellow "Camper" has them.

I'd love a follow up, once you get it shooting. Are you going to load them with a BP substitute or black powder?

Rates a definite Two-Cool

I think I have both BP and substitutes. I've never been a big fan of BP shooting but I have dabbled with hunting with BP rifles in the past so I have some old powder around.
If the gun does not sell then I will be getting dies made up. A fellow "Camper" is going to supply me with lead bullets, so that problem is solved.
If I get it going I will hunt deer with it here in Indiana as I'm currently rotating through my vintage European rifles so these old warriors get back out in the field.
I'll post progress here as it develops.

I hope you have patience or better luck than I did last time I contacted C4HD for dies. 1+ year wait

Looks like the gun is headed for a new home as it has received a bid.
Yes, C4HD warns on their website that they are covered up, so I was prepared for a wait.
I had another Cape gun a few years back that came with a set of their dies. I had questions about the caliber and did manage to talk with the owner and he seemed like a really nice fellow. He was more than willing to spend time on the phone with me even though I was not buying something.

It is a nice piece, congrats on your pending sale.