1957 D LWC Die Gouge?

a die dent... then tried to removed by abrasion ?

@lawest I may use your photo for educational purposes. If I do, I will use your CCF name, not your actual name!

I do think this is damage from a feeder mechanism, uncommon during this time.

In 1945, a Conversion Unit for Coining Presses (a Dual Coining Press) was designed by a machinist at the San Francisco Mint, Mr. William P Kruse, along with the collaboration of the Superintendent of Coining at the San Francisco Mint, Mr. Joseph Steel, and entered production. The patent was issued in 1949, (schematic below). It is likely that these conversion units were widely used and installed on Bliss Presses and any of the Ferracute Presses still in production. In 1945, it was reported that "This device can be used and is being used on all coinage, domestic and foreign of the sizes of quarters or less." It seems that it was a simple matter to attach the device to an existing press, which accounts for its almost immediate broad use. Coincidentally, while examples of these damage patterns are uncommon during the following ten years or so after its introduction, this mechanism is most likely responsible.

Schematic:

Excellent use of our historical data.