I've shot cast 350 grain (345-351) bullets in .452, .456, .457, and swaged in .458. Everything is paper patched. I've learned it requires two wraps, not one. Patching paper thickness varies with the bullet diameter. Still testing how far over bore to go, .001-.003".
The .452 patched to .461-.462 has done pretty well. The .457 Gould has done well. N for B mostly, using Ross's 40% rule. Started at 42 grains 4198, worked down, now working up and back around 42-43.
Olde Eynsford 1.5 was mediocre alone and as a duplex load.
Yes, Charles Lancaster made his / their own loading tools and bullet molds. Not specific to the oval bore, as they were in the .450 BPE class and shootable by just about any .450 BPE, but the exact diameter they used is what I'm after. Not mentioned in the 1889 Lancaster catalogue or in his shooting book. At the 1862 military shooting trials (Westley Richards, Alexander Henry, Charles Lancaster... The three great firearms minds of that time...why hasn't anyone done a movie about this?), the Lancaster ovals were shooting .442 diameter bullets, patched up to fit in a nominal bore diameter of .456. How much patching, using which "prepared paper," to what final diameter, I can't determine.