Wolf Pub, Phoenix had a paperback book out on the work of Rocky Gibbs, gunsmith. As I recall, he was Greek and came to US post WW II, initially Denver area. At that time shooting supplies were in short supply. There had been a war. One of his efforts was "duplex" loading of cartridges using 2 powders. Book had basic instructions. "Flash tube" was threaded into the primer pocket to carry primer flash up to near the base of the bullet. With powder funnel over case mouth and tube plugged, a faster powder, eg. 4227, was put into the bottom of the case and then the case filled with a slower powder, eg. 4831. Upon firing, the slower powder would start to burn and start the bullet up the barrel and then, like a turbo charger, the faster powder would burn for extra push. With the variety of powders that have been available today, I would not touch this with a 100 foot pole... but interesting history.
In a biography by Keith a friend loaned me, Elmer claimed that he was assigned to an arsenel during WW II as an activated member of the reserves. Salt Lake? Don't recall. Anyway, he claimed that he worked out a system by which using 2 powders, a "duplex load," he could get another 250 feet per second out of the Browning M2... With a 2 ounce bullet that ain't hay. He said he was recognized, thanked, and then the project was "put on the shelf" because there was no way to get the baggage apes that handled the ammo to not handle the ammo roughly, mix the duplex powders and create a VERY, VERY dangerous condition.
!! Luck. Happy trails.
