If you are involved with getting this brass produced, make sure Jamison has the dimensions right.

For us Martini shooters Jamison made 577/450 brass to CIP specs. This brass will fit a 70 percent of the Martini chambers. CIP shows the 577/450 shoulder as an angle flat plain when in fact Martini chambers have a ogee shoulder.

Kynoch and Bertram both understand this problem and make a an appropriate adjustement to the shoulder of their brass fits 99% of all the martini chambers..