Hey guys, I recently won an auction for a few choice rcbs die sets…included in the lot was a bunch of vintage rifle cartridges. One was a 45-75 WCF, a few 50 2-1/2” Sharps, and the guy pictured below. I can’t figure this one out! Some dimensions are shown in the pics, hopefully someone can help me identify what cartridge this is! Second pic from bottom shows the mystery cartridge next to a standard 45-70.