Having successfully developed loads for a couple of previous glocks, and a compact S&W, when I got my 5" SW I figured... no problem.
Well, multiple alloys, sizes, oal, crimps (no crimp, fcd etc) and powders later, I was still getting leading (about 1/3 barrel).
(for info sake. Size is always after PC)
I am not sure why, or for what reason, I double coated a batch of COWW.
Shot them. 99% of leading was gone
Tried same with range scrap.
Very little leading again. Came out with cleaning brush.
I guess I am not going to screw with success. I may try ESPC, as maybe this exposed problems with my dry tumble method... But an interesting find none the less. Can't say why, but it seems to help. Just takes an extra few minutes at the toaster oven on a casting day