I keep powder in the original containers with an old 1lb can around the reloading press/scale. When the 1lb-er gets low I top it back off from the larger containers.
If you're just trying to blend a variety of powder lots into a homogenous product then the container doesn't matter.
I use them up in the original containers according to lot #. Pour the remaining immaterial amount in the second to last container into the last container and mix it a little. There is no need to mix material amounts from different lots together. FIFO pulled/used inventory method for powder.
Well I’m trying to avoid any variances I’m lots so I would like to blend it all together and then put it back into the original containers. I have 13lbs from 6 different lots. If I make it all the same that should just about get me through this barrel before I need to buy more powder.
I think I might just wipe down a new 5gal bucket with dryer sheets and mix it in that. Then poor it back into the containers.