Thanks for the quick reply.
I can see no discernable "76, H, or HK" next to the Reichsadler. However, there is a very readable "K" stamped alone just to the right of the swastika circle of the Reichsadler. On the opposite side of the trigger guard there is another stamp which is difficult to interpret. It looks like a large letter "N" with some type of stick figure (person? dragon?) in the middle of it. This has the number 41 stamped directly beneath it which I assume is the year as it has a fairly early serial number, 31074. This unusual stamp is repeated on the barrel.