You cannot take the dimensions of blackpowder cartridges from that era as being written in stone. Tolerences between cartridge and chamber were loose because of black powder fouling and it wasn't critical. Expectations on accuracy wasn't that high either. They were more concerned with function and reliabilty of feed so small dimensional variations shouldn't be taken as a cause for concern. Different manufactures had their own ideas and as long as it fitted the gun and went bang nobody bothered.
Even today things vary. Take the good old .38 Special. Bore diameters vary from .356" to .360" ( maybe even .355" in the Colt Pythons which were always famously tight barrelled) although modern barrels are more closely controlled the older guns were often oversized. Hunt around and you will find ammunition that reflects that same variation. Espescially lead bullets because it doesn't matter with lead.
In years of reloading .38 Spec I found quite noticable fluctuations in case length too. Gevelot cases I remember were always shorter and required the seating and crimping dies to be re-adjusted to load them.
.45LC as well, is noticably variable. Bullet mold manufacturers list two diameters of molds for the .45 because the fluctuation is so great. .454" nominal for the old revolvers (which actually casts about .456-.458") and .452" nominal for the modern copies.Cases again have different lengths, only slightly but its there.
Parallel rimmed cases are not dimensionally fussy in the same way as a rimless rifle case would be.