Belt mountain "punch bullets"

I have recently read some, and heard some about Belt Mountain, who makes reinforced firing pins for large frame revolvers as well as lathe-turned hollow-base brass bullets (lead-filled base) for large-game hunting when a large-caliber revolver or lever-carbine is being used. There was a short blurb article in the April 2007 issue of Guns magazine on them. Apparently they offer .45 and .50 calibers currently for such loadings as .454, .45LC, .50 Linebaugh, etc… I have seen reference to these in .44 caliber also, but nothing currently shows this as available, and none of the major (or minor) suppliers or either of the auction sites shows anything for these bullets… Apparently these bullets punch through one side of a buffalo and out the other, clean through the shoulder bone, also have heard these punch through 50" of wet phone book…
Belt Mountain has a website, but it’s very simple, and no return on my contact to them yet.

Has anybody ever used or seen these bullets?

45-70 bullets pictured below: