The UMC Ledger has this to say regarding a .45 Turkish Spencer cartridge.
45 Turkish Spencer
Shell solid head made to the regular Turkish gauge.
U.M.C. # 1 1/2 primer - 81 Grains of M.H. or F.G.R. powder.
Bullet same as regular Turkish only flat point for
magazine purpose. Cartridge same length as Turkish.
I have two, both have solid head, one with a .175" Ø copper primer, one with brass primer. Both with flat point bullet. The “regular” UMC Turkish Peabody Martini cartridge is Berdan primed with round nose PPL bullet.
Based on the Ledger description, these may be “Turkish Spencers”. Were these used in a “regular” Spencer rifle, altered, I assume, to operate with these much longer cartridges, with tubular magazine in the butt stock, or, something else ?