Originally Posted by
goodsteel
Getting back to the main subject (before all the drama happened)
I have wondered the same thing about duplex loads but I dont think it would work to bump up a boolit because its not changing the reason why smokeless powder does not like to do this.
If you look at it, BP produces much less pressure than SP does but it almost always tries to bump the boolits. Whats the difference? SP burns and BP explodes. I theorize that the reason why SP doesn't bump the boolits is because of a gentler (albeit larger) pressure curve, coupled with the fact that the boolit is already moving by the time the part of the powder that does the bumping gets to the base of the boolit.
Having a duplex load would make the process faster perhaps, but at the end of the day, the cartridge has to burn a lot of powder before it gets to the base of the boolit.
BP doesn't have that problem, because for all intents and purposes, the powder all goes up right where it is.