Gunny, I also have a Tumlers Tumbler that I use on occasion as well as a Lyman vibrating tumbler with walnut media. As for the Tumler’s product, I have heard it suggested that the tumbler was rough on the brass but does a good job cleaning. I would suggest filling the drum full of water, not half full, to keep the brass from beating itself to death. I also add dawn dish liquid and lemon shine, a product I saw mentioned on the internet. You mentioned above, the inside of the case necks. The fairies told me to: take a(my 6mmBR) .243 brass bore brush, insert it into a cordless drill or something to spin it, while the brush is slowly turning take slivers of your oooo steel wool and allow the steel wool to be twisted into the bristles of the bore brush. Once you have a proper buildup of steel wool worked into the bore brush, then insert into the mouth of your cartridge case and spin being careful not to overdo it. The combination of oooo steel wool and the brass bore brush should not be overly harsh and should allow for a clean, very smooth case mouth, which in turn, should allow for a very consistent bullet release.