After finishing the box of bullets I made sized .431 and lubed with carnauba red, I checked the bore, and I had leading at the forcing cone, and about an inch into the barrel. The bullets were plane base.
I bought a .433 sizing die off a member here. And I made a dummy cartridge with it. It chambered, but with no room to spare. And it bulged the case badly, and didnt look "right". I didnt try shooting any of them cause I aint going to make ammo that looks that "off". Maybe If i had a resizing die that sized the case on the large size it wouldnt look like a goof, and it'd be okay.
So I cleaned it thoroughly.
The forcing cone, as always, seemed rough to me, so I figured heck with it. I chucked a cleaning rod section in a drill, and using a patch loop, turned a piece of scotchbrite pad in the forcing cone. I lubed it with hoppes as thats what I had handy. Dont get me wrong, I didnt grind the stuffings out of it and did my best to keep out of the rifling with the pressure centered. It did remove the machining marks after a minute or so. Then I turned a patch covered with the finest polishing compound I had (green) and that shined it nice. I will report back if this helps any.
Next I will try some gc bullets again.
I aint got to completely cure the leading issue to be satisfied, but Its got to improve a fair amount. If I had shot 300 rounds instead of 50, with the same amount of leading, i'd say, cleaning my gun is part of life if it dont get any better.