000 (.360") weigh about 65gr. each, at the most. The Hornady 000 I measured were somewhere round 60gr. due to being .350"(can't remember exactly).
: They are pretty light for calibre guys. The only way to make a ball lighter is to hollow out one end.
: I seem to recall the bullets for my .38 were 158gr. and I shoot 160gr. SWC from my .357 mag. at 1,350fps. They're still light for calibre, but penetrate considerably deeper than round balls of that size.
; Now, if you take a .44 Marlin and load 3, .430" balls in the case with a charge of Unique, you have a load that will grup in about 20" at 100 yards with balls heavy enough to do something. You might want to duck that one too. Still, it isn't a moose load.