Grafs and sons has 24 gauge reloading components. If you load nitro I don't know how you would get your loads pressure tested and I don't know what pressure the gun was "designed" to shoot.
These are the plastic Cheddite:
http://www.grafs.com/product/185062These are brass:
http://www.grafs.com/product/193264There are other companies that sell Magtech Brass hulls besides Graf's.
I just loaded some Magtech brass 16 gauge with black powder and it was a breeze. I got the wads appropriate for black powder and Magtech brass from "Track of the Wolf":
http://www.trackofthewolf.com/(S(5n55up4...amp;styleID=123Best,
Mike