Sorry for the delay, it's a blown out .45 2.6" / .45-100 basic case I called .475 Morrison, blowing it out shrinks its length to 2.5". So it will still shoot .475 Linebaugh as a "special" being a true straight wall. I have a double rifle project I initially planned this for, but a No.1 is the easy way to go about it, could cut the deeper chamber by hand and start load development the next day. Idea for the cartridge was efficiency, least recoil for the thump provided. Large bullet and a moderate powder charge, similar performance to .470 Nitro but on less powder.