I'm going to speculate that pistol was engraved sometime in the 50's/60's. There were a lot of old world engravers from Austria/Germany who set up shop in the U.S. after the second world war, or at least some of their families would come over. They would do "work" here or ship it by mail to the home shop in Europe, then send it back to the U.S. when completed. I have a very early Smith Highway Patrolman (no dash) that was engraved in similar fashion, not factory. I had it lettered to verify that question, ended up posting a picture on an engraving forum. One of the members was very sure it was the work of a known Austrian family of engravers from that era, trying to make a living after the war. Sure enough to give me a four figure value on the engraving by itself.