"Several reloading manufacture's make reloading sets for use with brass hulls."
I have a 12 gauge set from RCBS, and a 20 gauge set from C-H/4D. Both are 1 1/8" diameter dies that fit the RockChucker with the reducer bushing removed. Shell plates are a different story, I have 2 sizes for 12, and every now and then find a case that won't either. The plate from C-H, for the 20 fits every case I tried.
If shooting Black Powder or a substitute, I have never resized an all brass case. But you need resizing if using smokeless loads!
I just loaded 125, 20 gauge. 75grain FFFg equivalent (by volume) black powder or substitute (FFg will do, only a little slower); 16 or 17 gauge over the powder card; 3/4" of fiber wad; 7/8 oz. #7.5 shot; and a 16 or 17ga over shot card (same as over powder). This leaves 1/8" gap at top of 2 1/2 brass case. I fill this with a squeeze of "Gutter Seam Sealer" from Lowe's home improvement store (dry to touch overnight) and let cure 3 weeks before using. I shot a 4 day cured batch of 50 one time, I scrubbed my Savage 310, 1 hour each barrel. These loads are about 1225-1250 fps from 30" barrels. Recoil is normal for a 20 gauge, but they are loud! Let me repeat, THEY ARE LOUD!
In theory, roll crimping the over the shot card will work without sealant, but it failed for me over 50% of the time. The crimp is an absolute pain in the butt to remove!
Ivan