Yes, I still think your cartridge #1 is a Starr. I don’t have any factory dimension for the Starr. A number of years ago I purchase a “Starr” from a well respected auction house. The dimensions of my cartridge are very close to the ones you posted. Also your dimension match those listed in Barber’s “The Rimfire Cartridge” and as well as those listed in Hoyem’s “The History and Development of Small Arms Ammunition”.
The dimension of the 52 Spencer vary widely. The case length is usually shorter than yours. The case has a slight bottle neck or much more taper from head to mouth than the one in the drawing. The bullet is usually flat tipped or more rounded, The pointed 2 groove bullet on your’s is typical of all the CD Leet Starr cartriges I’ve seen.
As for the .58 Chabot. I’m not sure what it is. The only picture of a “58 Cabot” I have been able to find is in Suydam’s “The American Cartridge”. The dimensions given there are almost identical to those listed for the various 58 Musket cartridges he had pictured. In George Hoyem’s “The History and Developement of Small Arms Ammunition” he states “The .58 caliber Allin, Springfield or Miller probably was used in the Cabot, Needham and other experimental transformed rifle-musket tried out after the Civil War”. John Barber didn’t even mention a .58 Cabot in his book. Is there actually a 58 Cabot cartridge or did this conversion use the standard 58 musket? I don’t know!
The dimension of the 58 Musket cartridges in my collection match pretty close to the one you pictured except the rim diameter on mine are only about 18.0 mm verse the 18.8mm on your’s.
Thanks a lot !!!
Hum , you looks like to know very well the RF rounds !!
Do you know also the European RF ???