I think I figured out my small leading issue.

[Colorado4wheel]

Not that it was a big deal at all. I have a very small amount of lead build up in the throat of my KKM 9mm barrel. My 155gr bullets are sized to .357 sometimes just a little smaller. Well I pulled one after it was loaded today just to check my crimp. Interestingly enough the entire bullet inside the case was sized to .356". Not terribly unusual for Lead to get swaged down by the case. Got me thinking that maybe the throat leading is just a product of the throat swaging down the bullets as they enter the barrel. It never gets worse and I can shoot 1k's of rounds with out any lead build up in the barrel. Throat just gets a little bit of build up. Any thoughts? I'm not really worried about it, just curious.

[462]

Just by chance, are your using a Lee Carbide Factory Crimp Die?

Is your expander plug entering the case the same distance as the length of the boolit? I've found Lyman expander dies -- M-dies -- to be invaluable in this regard.

Boolits should not be swaged down by neither the case nor the seating and crimp dies. They should come out of the case the same size as they went in.

[Colorado4wheel]

Not using a FCD. I am using a Dillon Press and it has a expander on the Powder Die of course.

[CPL Lou]

I use the 'case mouth expanding die' that came with my 38/357 dies. Seems to expand the cases just a little more then my 9mm expander.
I first use my 9mm expander die so that I get the case mouth belled just right, then I install the 38/357 die and adjust it to go just deep enough so that the bases of my bullets are not swaged.
This adds an extra step in my reloading, but is well worth it.

Lou