That'll work!
Which is kinda what major powder companies do after producing a new lot. They save some of the previous lots that were faster or slower-burning than the ideal they were, uh, "aiming" for. They test the new batch, then if it's not within 2-3% of the burn-rate desired, they mix in some of the older batches to adjust the burn-rate.
This obviously is easier to do when the powder's been in production for a while, so there are more previous batches. When Hodgdon started offering the IMR Endurons a while ago (primarily due to a shortage in the supply of the Australian-made Extremes), they sent me some 1-2 pound samples of various powders to try. One of them was IMR4451, which was designed to approximate H4350. I was impressed enough to order an 8-pounder from a website, but it resulted in around an 80 fps difference in the same loads. So I mixed the first batch into the 8-pounder, and it resulted in velocities closer to their published data.
I had a friend that took this concept a little too far in my humble opinion. One day he mentioned his “duplex” loads for the .300 Weatherby, and since that piqued my curiosity and I also shoot a .300 Weatherby I asked exactly what his duplex loads were.
He rattled off three different powders, all with similar burn rates. He says when the containers get low he just mixes them all together. Mind blown!
