Charlie,
Walmart has Spectracide stump remover or at least the one near me does and less than $5 a pound. Couldn't find it at Lowe's.
Just added some home brewed dextrin to my 2nd batch of BP since the first batch is prone to crumble pretty easy. It takes a lot longer to convert corn starch than I thought it would.
My first batch of powder (not compressed) weighs about 60% of the same volume of Swiss. I loaded some 40-65 cartridges Friday night and plan to chrono them and shoot for group this afternoon. Had to come into the shop this morning to finish a job to be picked up tomorrow. The powder is definitely fluffy. Even when you compress it into the case there is very little resistance. I am going to try and put 20gr in the case compress, add 20 more repeat and once more for a total of 60gr and see how that works. Right now I'm shooting 65gr of Swiss under a 405gr Brooks boolit.
Charlie, post some pics of your compression set up when you get it built. That is my next step.
Bob