Years ago, the TC Mag Express Sabot may have been the MMP standard "Black Sabot",
http://mmpsabots.com/store/black-sabot/, not either the HPH-12 or 24. Since then, it may have been supplied by a variety of suppliers. Pictures on the Midsouth site look similar for the Hornady, and the TC. I don't know if the current TC is produced to a specification, by Hornady, to be similar to the "TC Black" or if it's simply identical to the Hornady branded item. Other sources here have said that the "TC Black" is similar loaded diameter to the HPH-12.