The character with the 'N' under it is an eagle with spread wings. This is called the 'Bundesadler' and roughly translated means 'federal eagle." It is used on many German federal insignia. The 'N' stands for "Nitrozellulose" (Neetro-tselluloze) or "Nitrocellulose" in English. This is a universal symbol found on German firearms that use modern nitrocellulose based propellants.
The symbol to the right of the date code is a stag horn. It is the symbol of a particular proof house, located in Ulm, Germany. German firearms are sent to proof houses before sale, for inspection and quality control. This is much like a 'UL' listing for American small appliances. There are other proof houses, for example, in Kiel and Hannover, Germany, but HK uses the Ulm proof house exclusively. Here is a link to the
Beschussamt Ulm web page: (In German)
