You’re right!
Assuming that all of the powder reacts and is ejected from the muzzle, I suppose that the ratio should be relative to the inertial mass of the cartridge minus the inertial mass of the casing.
I suppose that, since the question posed was for a 45, one also has to take into account the ejection of the casing as well.
i’ll make it easier on ya... the gun is a revolver! :)
Yes. Since the casing is ejected (more or less) sideways, it would act as a torque on the shooter to increase his angular momentum (that is, he would start spinning).