Found this add in an old "Guns" magazine from the sixties (https://gunsmagazine.com/classic-iss...zine-editions/)
A "streamlined" shot pellet which would not tumble in flight would be a tremendous boon for a long range turkey load or a serious goose-getter. But wrapping a pellet in "natural or synthetic rubber" and expect the pellet to achieve a "teardrop shape" in flight is stretching it a bit - Pun intended!
The patent papers can be found here: http://www.freepatentsonline.com/3400660.pdf