FIrst off, welcome to the forum! And welcome to the world of P38 collecting. Your analyste of your P38 is correct. A nice wartime P38 made by Spreewerk in 1944. It is well worn, but honest wear, and I personally like that a lot!
As others have mentioned, the "511" marking on your P38 is a frame number, or assembly number for the frame. It has nothing to do with the serial number, so no need to worry about it not matching your serial number.
Matt
As others have mentioned, the "511" marking on your P38 is a frame number, or assembly number for the frame. It has nothing to do with the serial number, so no need to worry about it not matching your serial number.
Matt