Okay I changed my mind about carb out.
I found an 8mm copper brush in my gun cleaning tote. I let carb out soak for 20 mins, brushed the hell out of it and ran a patch through. Came out black
Finally some headway; I’ve been cleaning with hoppes and a nylon brush (super unusual for me; I usually just use patch out on rifles)
and wipe out and everything was coming out “clean”. Even did a few patch out runs following the 5 min soak patch method with no results.
If I can get this thing to look less like a shotgun bore and finish the ~800 rounds I have left I will be a happy camper