Re: anyone know load data for old .32 H&R
According to U.S. Cartridges & Their Handguns by Charles Suydam, your revolver takes a long-obsolete cartridge, not made for about 100 years: The .32 Merwin, Hulbert & Company Long.
Suydam gives .32 M&H Long cartridge dimensions, measured from old cartridges, as:
Rim: .374 to .375 inch
Head, ahead of rim: .338 to .339
Case mouth, below crimp: .309 to .339
Bullet diameter, maximum over rings or belts: .309
Case length: .874 to .890
Overall cartridge length: .1.206 to 1.236
Bullet weight: 88 grains
Propellant: Black powder, 15 grs. (grade not mentioned, though I'd use FFFG).
Interestingly, Suydam reports that no headstamped cartridges have been seen, although it was made by Winchester Repeating Arm, American Metallic and Union Metallic Cartridge.
The late gun writer George Nonte, in the March 1961 Shooting Times (p. 20) has an article on forming obsolete handgun cases. To create this the .32 M&H Long case, trim the .32 S&W Long case to .890 inch, he wrote.
Suydam reports that .32 S&W Short cartridges will fit in the M&H revolvers. As you noted, I'd be leery of using smokeless powder in such an old revolver.
Stick with black powder loads, a soft lead bullet and SPG or Lyman Black Powder bullet lubricants, designed to be used with black powder.
I'm not sure where you'd find 88 gr. .32 caliber bullets. I wouldn't use the common .32 S&W Long bullet, because it's 10 grains heavier -- a 9 percent heavier bullet. Even when new, many of these old revolvers were not particularly strong. I recall seeing an old Forehand & Wadsworth pocket pistol with steel between each chamber not much thicker than construction paper!
Sounds like you have a fun project ahead of you. Hope the above helps.
"Therein do I see an ugly cat. Smoke. Fire. Brimstone. A vast desert. Holes in parchment. The ugly cat is much amused." --- The quantrains of Gatodamus (1503-1566)