I am a bit confused.

I did not say it was converted to .45-70.

I just suggested that .45-70 would be my first 'suspect'.

My second 'suspect' would be the similar 11.7mm Danish Rolling-Block cartridge.

In my opinion, it is essential that the dimensions of the chamber and bore, as well as, the quality of any 'alterations' be determined directly by a competent gun person and not based on internet guesses.

As FredC cautioned: "Beware of Bubba Work" on that barrel and chamber.