I use retumbo on occassion. Seems to work nicely. But has the longest muzzleflash I have ever seen. I have a 190gr matchking load 96gr of retumbo, and it puts a flame 4ft out the barrel. Flash goes down some when you move up a few grains but accuracy went down. Others have observed this and Sierra techs thinks it the coating they use.

I have had one instance of good luck with Reloader 25. Seems to vary some from lot to lot however. It is the one powder you can probably get max velocity.