A 147gr 9mm loaded to 125000 power factor will tend to shoot softer than a 115gr 9mm loaded to 125000 power factor.      Like Matt said, its because power factor is a momentum calculation.     Same result in all calibers:  180gr 40 loaded to 125000pf is softer than 155gr 40 loaded to 125000pf.

Course some shooters still prefer the lighter bullet for cost or they actually prefer the way the gun feels with the lighter bullet.    But I think you'll find most go with the heavier bullet to play this game.

You can't really buy factory ammo to test this theory because the various bullet weights won't be loaded to produce matching power factors.   

MarkT
A32608
SSP/MA (TXst2011)
ESP/MA (TXst2012)
CDP/MA (TXst2013)