Well, I had to go out and shoot today after work for some stress relief. I wasn't able to do any more scrubbing on the bore to get the teensy bit of lead that was left (if it was lead) before going.
These rounds were 457193, 4gr 4227, 68gr 2F, a single 0.025 hdpe wad, compressed probably ballpark 0.25". Virgin brass, so the neck tension is what it would be with my 0.456 expander on the 0.460 boolit.
One thing to note on my virgin brass, is that I also chamfer the case mouth lightly. Not sure if that matters.
I think today may either provide an answer, or more questions.
The accuracy was better than last time. I had about 5 shots in 1.5" at 50 yards. The burn was a little more dirty... I looked down the bore every few shots and there was now leftover powder fouling, where I wasn't seeing any with 7gr 4227 and 65gr 2F. I wiped the bore every 5 shots or so to try to keep the fouling from throwing things off. Still saw lead on the patches.
Got home and cleaned the bore. There was about the same amount of leading as last time, throughout the barrel and not in any particular location. Lands, grooves, etc. I noticed with my borescope that there was a very scary looking deposit of lead all the way around the end of the chamber, right on the transition from chamber to leade. So, I think something is happening either with my loading (brass/lead interaction) or the size of this boolit (0.460) is possibly slightly too large for the leade and is collecting lead on the edge of the chamber mouth? I didn't notice this before... i can't remember if I inspected the chamber last time I cleaned it, but I don't think I did. Is it possible this stuff is actually HDPE from my wad?
It's kind of hard to tell, but it looked like lead to me when looking at it on my screen. Those white strings are from my patches.
Here's a picture with a fired case in the chamber after cleaning the lead out.
The other part is, I think I've got some rust spots starting in my bore... which really bugs me. I clean it within thirty minutes of finishing shooting. Water with a drop of soap in it on patches till they're clean. Then to remove the lead, I use a brush with some bronze wool and copper chore boy wrapped on it. After 15 passes, I'll wipe the bore out with a couple of wet patches, then a couple of dry patches, then oil it. So how am I getting rust? Does it look like the start of rust to you guys? After seeing this, I put a couple patches of sharp shootr tactical advantage (a copper and carbon cleaner) down the bore and my patches were bright rusty orange. Do I need to completely remove those spots with something? I've never dealt with rust in a bore... Anyway, I got some ballistol to clean it with the oil/water mix next time.
First picture is before using the cleaner. There were quite a few areas that looked a lot worse than this. Second picture is after cleaning. White splotches showed up after wiping out the cleaner with hoppes and drypatching.
This is making me feel like i've never shot a gun before haha