I am a first time user. Please advise me if I am doing this incorrectly. I hope that by posting here someone will be able to tell me what this large rimfire blank is. The OA length is 2.1 inches, the rim dia is .605 the base is .503 and the case mouth is .481
Welcome, and thanks for posting a quality photo with your inquiry.
Those who know more than me will be along to fill in the blanks, but in the mean time, it isn’t actually a rimfire. It’s an inside-primed centerfire 45-70 cartridge using the Benet priming system (there should be two crimps shortly ahead of the rim holding the primer in place). The headstamp shows in was manufacatured in June 1881, the F indicates it was from Frankfor arsenal. I’ll let someone else answer for the R rather than tell you what I think I know.
R is for rifle, C is for Carbine
Recent IAA thread about 45-70 identical headstamp to yours.
I found this picture on the internet while trying to find examples of wide vs narrow inside prime crimps.
Thank you very much, though I realize this has been a terribly slow response to your assistance. I only just found out where to find the responses to my original post. Anyway, this is both interesting and informative, again, thank you.