OK, I can understand that toothpaste is a mild abrasive but in each instance mentioned, the shooter had worked the action significantly to smooth it out - i.e., sit in front of the tv and work the action for hours on end, sit on the couch and cock and release the hammer on my 1911, and so on.
Years ago, like about 40 or so, I was told that the graphite lubricant in the tubes that came in the rifle and pistol cleaning kits was supposed to do just that, and that if you applied it to the action or moving parts and worked the action back and forth for a couple of hours it would smooth things right out. Of course it will, you're working metal against metal and eventually things will smooth out. I wonder if it might work better using something like Crest Extra Whitening formula..........
I used to do this with my M19s, or at least those that needed 'smoothin'. Now I do the same with molybidum or molybendum, er whatever it is and it works the same.
Actually, I think it's a hoot to paste a piece but don't use Pepsodent and a Shoot'n'See target 'cause ya'll might wonder where the yellow went.............................. Mikey..................................