First, thanks to everyone for their expert knowledge and friendly feedback. I need another area of firearms interest like I need a hole in the head, but this Luger stuff is fascinating.
DonM, I wish I could tell you what that letter or marking is. I took these pictures with a camera that was new to me, and this was the day before I posted here. I didn't figure out that I was taking the pictures without flash until afterwards, and this is why the picture quality is lacking.
The person who owns this weapon is a very nice lady who I met through an friend. I stopped by her house to appraise a group of weapons so that she would not get taken if she sold them.
I don't have access to this weapon. I don't think she plans on selling it, but I didn't want to give her a value on something I know nothing about.
Again, thanks for all the information. I will pass this along to her. If any of you ever makes it out to Phoenix, AZ, drop me a message so I can buy you some beers.