Well By Golly
Yes to all of the above . . . . "mostly" Unfortunately, I cannot confirm nor deny ownership of APP. As far as I have known, AMERICAN PIONEER POWDER is their own entity.
BLACK MZ is/was manufactured by APP and reflects the same same patent information as APP Powders.
The Shooters World product is Black MZ renamed and differently ground (I think). As far as I know it is the same granulation as 3F APP and as such should/will meter well thru most progressive measures. It will also require a certain degree of cleanliness following a loading session (should be done anyway, YES??)
I may indulge in more research, although, so long as I can source APP in quantity without problem, I must admit, I don't care (sometimes I are such a SNOT
)