50-70 Govt

I bought this cartridge a few weeks ago. It’s a 50-70 Govt bar anvil primed.
The Dim. of this cartridge match other 50-70’s that I have. I can’t find the bullet in any of the books that I have. My question is if the bullet is original or did someone butcher it

I had corresponded with Carolyn earlier regarding the bullet on this cartridge. It is very similar to the bullet on a Benet-primed .50-70 on page 49 of George Hoyem’s The History and Development of Small Arms Ammunition that he refers to as an ‘experimental Dimmick bullet’. Does anyone have any information on the Dimmick bullet, or know if Carolyn’s bullet is a Dimmick bullet?