The HS hulls come in 12, 20, 28, and .410. It appears that the 12 and 20 hulls can be used in place of the old style AA hulls in reloading recipies, but not the 28 and .410. The Claybuster wads I use in 12 indicate on the bag that the wad was redesigned for the new HS hulls. Apparantly the internal collar in the HS hulls would sometimes catch the edge of the powder cup portion of the wad and cause a hangup, resulting in either a damaged wad or a cocked wad. I suspect that the smaller volume of the 28 and .410 HS hulls is why new reload data is required, including specific HS designed wads. Have not reloaded any of the HS wads in 28 and .410 yet, so I don't know what other hangups they may present.