Hello Gents,
Please find hereafter an interesting photo discussed at page 43 of my book: "The Luger Artillery".
As already highlighted the grip of P08 was standardized starting from August 1913 including a stock lug. The internal area of the grips towards the bottom of the recoil spring changed. From right to left: a P08 made before 1913;
a transitional model with the stock lug and internal working unchanged ; the final frame configuration.
Should be interesting to add to your research also the transitional model to figure out the serial number range where this model falls.
Mauro
