458 Lott chamber question

[Buster95]

When you look down the barrel of a 458 Lott the little step (little shoulder) is very visible? The pic below is an example of the little step in a 45-70 chamber because I cannot find a diagram of a 458 Lott chamber.

 

[CTDolan]

Here you go, SAAMI specs on the Lott chamber.

http://www.saami.org/pubresources/cc_drawings/Rifle/458 Lott.pdf

 

[Buster95]

Thank you very much!