I’m using Magtech hulls here, but Rocky Mountain Cartridge, and Track of the Wolf also currently make these in multiple gauges. You can also find antique ones that also will work.

If you’re looking for more load data check out Ballistic Products. They have a manual just for brass hulls. Track of the Wolf also has a 10 gauge pamphlet (as well as many of the tools you might need). As always, have your guns checked out by a competent smith before use. Enjoy!