Leading really depends on a number of issues, only one of which is velocity.
In years past, my son and I both had Ruger Blackhawks. In his, we need to shoot a gas checked bullet to prevent excess leading, while mine was very happy with plane base bullets.
These bullets made from WW and were not quenched or heat treated.
We never measured barrels or throats etc. to find the reasons, as with the preferd bullet leading was a non-issue.
My BH has long since been replaced by a number of different 44s, but the son still owns/shoots his and we still cast the prefered bullet for that BH, no problem.
Keep em coming!