Be careful with the Federal Estates, they have a paper based inner wad that has been known to loosen and could lodge in your barrel.
This is especially true if you find them after they have been lying on the ground after a dew or rain.
I use the Cheddite red hulls that come primed already that were available from Grafs. They were 2 9/16" and I roll crimp them.
The black Remingtons are good if you can find them.
Larry, where did you find the "even lighter 20's"? They are about the hardest shell to find in a light load. I would reload them to 2 1/2" and roll crimp them, but I have only found a few loads light enough to use. These were 2 3/4" 6 fold, but will work in a 2 1/2" hull roll crimped.
