There are a few local gun stores on my travel paths that tend to stock more obscure stuff. Your (approximate) location would help drive recommendations.
I had a couple of boxes of Fiocchi, but they sold a long time ago. That's about all that's out there.
If you are around SE CT, I have some .454" diameter Hornady bullets and some .455 Webley brass, but I've not perfected my reloads as yet. I was attempting to reload with .45 ACP dies, but the one chance I had to test them in a Webley cylinder was unsuccessful and I dropped the effort. With a firearm in hand, I'm sure we can roll suitable ammo, if interested. At worst, you could acquire the dies and then it should be a snap.