Hodgdon was good enough to dig this week and report that there was a single pistol test table they shared for Titegroup (not for IMR4227) for a 300gn cast boolit in .45 Colt with pressures around 14,000 and it shows the charge with sized to .454 @ 3.7gn - 4.7gn Titegroup, velocity 614-737 fps.
For the 1885 High-Wall in particular, how about some feedback on molds and throwing .45 300gn lead. Anyone been down this road?
In the mean time I have a NOE .454 caliber Plain Base 292 Grains tumble lube design coming in.