I think Sisk bullets were primarily for rifles, all in .22 caliber and lots of different shapes. Sisk made true custom bullets, jacketed bullets only, and all of them were swaged by hand. His processes were not automated. Varmit hunters loved his bullets.

There are a lot of interesting little details regarding Sisk bullets.

During WWII, copper was what was then called a "strategic metal", and was in short supply for using as a jacket material. Sisk apparently began scrounging used .22 rimfire cases, and using some sort of press, formed them into jackets for his bullets. You can recognize these bullets because they have the original .22 cartridge head stamp on the base of the bullet along with the original firing pin imprint. Remington-UMC cases seemed to be Sisk's case of choice.

There's a good bit of information on R. B. Sisk and his bullets on the Internet. That's where I got this info.