17.6 = .693" and 17.9 = .705"
1898-1910 the choke & bore stamp was "Choke 18.2 17.6"
The choke over bore stamp was used 1910-1924.
I wonder if the 17.9 & 17.6 over 18.2 were the original dimensions, and it was reproofed and restamped after the barrel and chokes were honed?

Last edited by revdocdrew; 02/15/09 04:27 PM.