Page 298 or
The Parker Story the first Acme Steel barrel CH was 101184 made in 1900 and the highest serial number Titanic Steel barrel was 156622 made in 1910.
The early Acme Steel barrel guns I've recorded have the same K in the barrel steel location on the right barrel flat as the Titanic Steel barrels have from the get-go. Like 130114 shown here --
130114 11 K in barrel steel location.jpg
130114 10 ACME STEEL.jpg