43 Spanish Chamber

[Steveu]

I acquired a Argentine 1879 RB with a mint bore. I did a cast form mid-case up to .9" into the barrel. Groove diameter is .441", the neck seems short at .225" and the shoulder length is .150". I did a cast of the Lee sizing die to see what it was and the shoulder length is .220", which from what I have read is the correct length. So the question is, what chamber do I have?
Cheers,
Steve