It was Winchester and I think 32 gr. bullets made totally from "tin". It had a velocity of around 1650 fps and really greased up my bore something terrible. I finger coated them with LEE alox and stopped the "tinning". Why didn't Winchester do that in the first place?! They did seem softer than the normal 36 gr. lead alloy and readily expanded.
He said they made a .22 WMR version too for lead free markets.