I think the first ad is from after Benko opened his own business in Wrentham in the late 50s/early 60s.
I still get a chuckle from his comments about the ATF's opinion about the StG44, MP40 etc. on the walls in his shop, made in a mix of German and English, whereas the German was with a dialect from the Frankfurt area. IIRC he was from Preungesheim which is a quarter of Frankfurt. That was back in 2003. Ten years later I sat at his bed at the Giessen University hospital when he suffered a terminal stroke on his last trip to his Homeland.