When did Uniwads disappear from the shooting scene? I believe they were made by a company called Precision Plastics in CA. I used them in Federal Papers, Federal Champion IIs, Winchester AAs, and Remington RXPs with great success. The X-shaped anvil that fit down inside the wad would adjust to your shot column when you crimped it, so that the entire column would be down inside the wad. When you fired, the anvil collapsed even more, so that the shot were protected all the way out the barrel. Great wads and made for great patterns.
Or am I thinking about Trico wads. An old memory is a pitiful thing.