There are a few missing pieces from the picture you painted. Things to help answer your question more effectively include: What is your bore diameter? What diameter have these bullets been sized to? Did you sufficiently bell the case before loading? (ask me how I know this can shave a perfectly good bullet into an undersized leading machine)

If you iron out these pieces, get a bullet loaded that is .001 or preferably .002" over the bore diameter and still get leading then you need to look a little deeper like what are the diameter of each of the chambers in the cylinder (under bore diameter and it will always lead until it's reamed out). Or there can be a stricture in the bore where the barrel attaches to the frame (like my 627), the solution for mine was firelapping.

Sounds like you have some investigating to do. Good luck.