Here you may also find the many different shapes of crowns as they indicated rank of nobility in the various empires and realms:
http://en.wikipedia.org/wiki/Heraldic_crownOr, in German:
http://de.wikipedia.org/wiki/RangkroneI too read the monogram on your drilling as "Freiherr = Baron A. von R."
Americans are usually ignorant on the meaning of the different shapes of crowns. To them most often any crown is a crown, certainly indicating former ownership by the Kaiser or, at least, a king. Two examples from questions dropped at my feet: There once was a lavishly engraved, carved and gold inlaid Tesching = blackpowder small bore / rook and rabbit rifle. As the tang is inlaid with a crown and a big W underneath, it was advertized as "Kaiser Wilhelm's favourite plinking rifle". As the crown was the type with just five tines, it never even came near the Kaiser, as the original owner was a simple, untitled "W. von …", the lowest rank of German gentry/nobility. Before 1918 successful industrialists, inventors, politicians, poets and so on were often promoted to nobility by having a "von" attached to their name, see f.i. Nicolaus von Dreyse, inventor of the Prussian needlegun.
Then there was a Haenel M1909 rifle, engraved with another crown and the letters J and F.

The owner hoped it once belonged to Austro-Hungarian emperor Franz-Joseph I. But Franz Joseph was already 79 years old in 1909 and abhorred bolt action hunting rifles. The crown is neither the imperial Austrian nor the royal Hungarian one. This crown is a "Fürstenhut" = princes crown and by the address of the retailer was in south-western Germany, I was able to identify the most likely original owner: Fürst = Prince Johannes Friedrich von Hohenlohe, 1863 - 1923.