I will use mouse phart loads in my 38 and 9mm at bare minimum
manual data but, I also use a single stage and a loading tray.

With a jacket and a light load of any fast powder, I NEVER use
a starting load....
and usually add .3 grs to the lowest load, just because the bullet
has a copper jacket on it !

No problem with lead but copper takes more powder to get it to clear the barrel.
I never had a jacket bullet shoot well at bare bone fps, any way.
Try 4.3 grs of w231 with a light crimp and see what happens.

It might be time to clean that loader............... ?
or at least make sure it is in proper working order.
Way too many errors in that amount of shells loaded.