My dad had several old Colt moulds. We used the .44 caliber ones to cast balls for his original percussion revolvers, which included a Colt M1860, a Remington 1858, and a Starr single action. There were no problems that I recall, although we never did any serious bullseye shooting.
I haven't been able to re-locate the reference, but I'm pretty sure I read somewhere years ago that Colt did a brisk business selling moulds by themselves, and not just with his guns. I don't know when that pivoting sprue cutter was invented, or if Colt was the first to market that type of mould, but it was apparently very well received by the shooting public of the time, and Colt's .454 ball mould may be the reason there are so many old percussion rifles in .47 caliber.
I don't collect old moulds, but dad sort of haphazardly acquired a number of them. His collection is in the family, although not in my possession. Like so many of the original products that came from "under the Blue Dome," those old moulds were nicely made and very functional. I think a lot of the modern replicas are intended for display only.
I recall you acquired quite a trove of old revolvers not long ago. Did you get moulds and other accoutrements with them?
Best regards,
Notchy Bob