[Augsburger]

I finished my Erfurt collection last week with a nice 1914 and am now ready to start with the Axis era. I would like to start looking for a G date but cant figure out from the references here what the difference is between a "G" date , P code , S/42, and K date are. Looking for a copy of Axis Pistols but until then I need some basic info. Also, what are the correct period mags for G date Lugers. If someone could point me in the right direction I would be most grateful. Cheers!