Originally the .38 S&W was loaded with a 145-150 gr round nosed bullet, and 14-15 gr of black powder.
The .32 S&W was loaded with an 85 gr LRN over 9 grains of black powder.
(Source: US Cartridges and Their Handguns, Chas. Suydam, 1979)
A black powder CARTRIDGE should have NO air space between the powder and the base of the bullet, or it may act as a barrel obstruction. The powder charge should be slighly compressed when the bullet is seated.
I would check with a good powder company of two for their suggestions for a SMOKELESS load. If you stay clear of very fast powders, you should be able to do light smokeless loads that will be good for older revolvers. And far less messy to clean up.
What we have here is... failure- to communicate.