Sound Advice from the "Experts ".
I picked up another Reloading Manual at a gun show , Modern Reloading Second Edition , compiled by Richard Lee of Lee Precision , makers of Lee Reloading Equipment.
This is for all " Smokeless Powders " in chapter 8 , "All About Pressure " one paragraph in particular caught my eye, it states ,
"A duplex load is a concoction of fast and slow burning powders in an attempt to sustain peak pressure longer. It does not work, so do not try it. It's very unpredictable and extremely dangerous. Never mix powers.
It mentions various things that have been tried. Then goes on to say ,
The schemes above are mentioned to point out that almost everything's been tried. Ammunition making is a well developed art where there is little room for improvement. Stick to proven loads .There is a wealth of excellent load data available. This is not an area that experts can improve on so there is little chance for amateurs to succeed.
There you have it , in black and white from experts in the field, "warning of dangers of duplex loads " using smokeless powders, as we do in our smokeless muzzle loaders.
Bolding is mine.