[Researcher]

From all the photos I've saved, I see the sort of ampersand symbol appearing very regularly once the J.G. in oval stamp of Jim Geary begins appearing in about the 162xxx range. I see the ampersand symbol pretty regularly into the 180xxx range.

163016 03.jpg

162759 02 big P.S..jpg

159801 01 DH 8-gauge, 6 frame.jpg

180703 01 30-inch.jpg

Here is one in the 174xxx range that also has the two dots.

174616 02 KL3 K = May L = 1942.jpg