Many thanks for the very useful data and advices.

US powders are not available here... so I use VECTAN Ba10, which I understand to be very close to Bullseye although eventually slightly faster.
Vectan powders reloading charges here:

Discover which powder corresponds to which rifle or revolver

So I will start developing the load for the 52-2 with this powder.

The serial number of my pistol is: A485711, I believe from the early 80's?

Again many thanks for the warm welcome and help!