u bad, but........

most companies try to put out their powders to match a specific energy
that puts out the same fps out of their test barrels, before they
put it in containers for the public.

However this does not always happen.
One reason a powder might not be on the shelf, until they get it right, or they think it is "Close enough" and let it go out the doors.

A big vise and long string is always handy to have around.