USAC plastic cartridge cases

the top of the box it says, “used only in USAC plastic cartridge case” And on the side of the box it says“38 caliber .357, 148 grain full metal jacketed wadcutter. Used like the Speer plastic case & bullets. " The case is plastic with a metal head and rim. Those funky looking bullets were to be loaded with the reduced diameter shank in the plastic case, with a ridge in the plastic snapping into the groove in the bullet to serve in place of a crimp. An interesting gimmick that went nowhere. Shares of stock in USAC were selling for 25 cents before the company folded completely." http://www.thehighroad.org/showthread.php?t=483591