The February 1943 issue of the American Rifleman has an excellent article on bullet lubrication.
In that article is the old factory recipe for the lubricant used for outside-lubricated bullets, such as the .41 Long Colt.
The recipe calls for:
1 part paraffin
1 part tallow (I use mutton tallow from Dixie Gun Works)
1/2 part beeswax.
All measures are by weight, not volume.
I use this ol-timey lubricant all the time and am quite pleased with it.
I use it for outside-lubricated, heeled bullets in the .32 Long Colt, which is fired in my original Marlin 1892 rifle.
Felt wads for my .36 and .44 cap and ball revolvers get dunked in it. Patches and over-powder felt wads in my .50 Hawken are soaked in this lubricant.
In black powder pistols or rifles, bores are left very clean when I use such wads. Without the wads, not so clean.
Soft lead bullets in my .44-40 and .45-70 rifles, loaded over black powder, are lubricated with it. Bores are left very clean if enough lubricant is used. If the bullet does not contain enough lubricant, I use a felt wad soaked in the lubricant.
Heck, I've even lubricated hard-cast bullets for my .357 with the stuff and it prevented leading up to 1,200 fps or so. I haven't tried higher velocities in my .357 with this lubricant so I don't know how it would fare.
I suspect it would work well at any reasonable .357 velocity (1,500 fps or so).
The above recipe very closely resembles the SPG lubricant sold today. Most people would have a hard time distinguishing between them.
Assembling ammunition with outside lubricated bullets requires more reloading steps, and requires more care in storage to ensure that the lubricant doesn't pick up crud and grit, but the dividend in old guns is often better accuracy than the hollowbased bullets.
Someday I'd like to have a .41 Colt to tinker with. I envy your project.