Jack,

I believe you are correct in all of your assumptions. A replacement barrel without the correct two step notch for the mushroom knob would be supplied with the then current barrel knob that matched the notch in the barrel. This is the usual case when barrels contemporary to the gun's original manufacture are no longer in inventory.

Where is the 360 stamped? I suspect it's not significant to the work performed other than being the code of the workman that performed the work unless it went 'home' again in March 1960. Month and year codes are much more prevalent than month, day and year.

A letter will not have information about the rework. However, once it's obtained, a request can be made to the Hist. Foundation which has completed digitized files for the period of the 1930s and you will be able to obtain repair work information.

__________________
Jim
S&WCA #819