Ummmm... looks to me that somone tried their hand at reviving the "explosive bullet." In the 19th Century, during the height of the professional hunting on the Great Plains, there were moulds available to make a bullet was a gaping hollowpoint. The diameter of the hollowpoint would fit a .22 calibre blank. When the bullet was fired into animal flesh it would detonate the priming compound and the powder charge in the blank would cause the slug to fragment. An example of this is listed in the Sharps Rifle Company's catalogue of 1879 as the "Express Bullet." .45 cal, 298 grains, oriface .22". No price was given. They look just like the old .45 cal, 330 grain Gould mould that Lyman produces except the hollowpoint is smaller.
I read an account of these in The Black Powder Cartridge News. In the letters of Charles Hatch Billinghurst, he details using them on an elk. Issue #54 Summer 2006, page 33.
"Hal and I had moulds for making hollow pointed bullets. we could put a .22 shot cartridge into the bullet and make an explosive of it. Hal shot an elk on the shoulder, yes on is right [sic] for the bullet blew all into little bits and didn't penetrate. Hal was disgusted, nothing but solid bullets for him after that. I killed my first Mule deer with hollow bullet. It rolled out like a mushroom, tearng a big hole. We decided that a solid bullet was good enough."
Looks like someone just tried the same idea with a .303.
