It's not for your average reloader.
Small changes to one of the powders in a duplex charge can be HUGE differences in internal ballistics.
Most duplex loads are brewed up for one specific case/primer/bullet combination for one specific firearm.
__________________"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.
