Not really that new:
October 1904 - this advert tells that: gas is introduced into the shot charge to promote the spreading effect.
"Less recoil and practically the same velocity".
December 1904 - no mention how the Big Red W did it in 1904
"without the sacrifice of velocity, penetration or uniformity". I remember seeing a cross-section of a spreader shell in one of my old
American Field papers, showing layers of thin card wads in the shot charge. Kind of like a layer cake. But I don't recall if that was Winchester's design. I'll post that illustration when I come across it again.
