My take is that the
K and the
Kf are the barrel steel marks. But no one left alive knows what they signified other than what we can observe which is that the
Kf is found on barrels marked Vulcan Steel on the rib and that the
K is found on barrels marked Titanic Steel and Acme Steel. I can't imagine that if Parker Bros. was springing for Krupp tubes they wouldn't have marketed them as such.
The highest serial number gun I've recorded with the
K in the barrel steel location is a 10-gauge DHE 146730 that also has the WK in an oval stamp on the left barrel flat.
http://parkerguns.org/forums/showthr...=146730&page=2
Another thread on this topic --
http://parkerguns.org/forums/showthr...ghlight=146730