The old ammunition catalogs from the 1930s usually show the MV of the .38-44 cartridge as being in the low 1100s from a 5" barrel (158 grain lead or metal capped bullets). However, they do not specify if that MV is measured from firing in an actual revolver or from some special test barrel. I suspect the latter.

The only way to accurately know the MV of any load is to chronograph it in your own revolver. For those who have not tried it, one can see very significant variations of chronographed MV among various revolvers with identical barrel lengths and loads. I have always speculated that the cause is due principally to differences in the cylinder-barrel gaps.

Old Lyman reloading handbooks from the 1950s give heavy .38 Special recipes using only 2400 powder, usually in the 11-13 grain range, with 158 grain cast bullets. This is probably because of the small number of suitable propellants available at that time. They do not call such loads .38-44. They only suggest that such loads are intended for use in "heavy frame revolvers."

FWIW, I have calculated peak chamber pressures of the .38-44 to be around 25,000 psi using the Quickload internal ballistics software and 2400 powder with a 158 grain lead bullet, assuming a MV of 1150 ft/sec. Whether that reflects reality from a revolver I have no idea. But it's probably not far off.