Yeah... Problem with the 45 acp is that it is low pressure which is not really a 'problem' but as such uses fairly fast powder that is designed to burn completely in a 5" barrel. When you get to 16" barrels there is not much gain in velocity. I think those defense rounds are probly worse since most are made to be 'low flash' and low recoil. Which most likely means a shit load of fast powder.
AA#5 was actually developed to duplicate the original loading for pressure curves and burn rate... It is a medium burn rate powder at low pressure.