I have a couple of GH grade guns in the shop with the reinforcing rod in them. One is in the 104,000 serial number range and the other is a 86,000 serial number range.
The 104,000 gun has no markings on it at all in regards to a patent stamp.
The 86,000 gun has both the stamp on the toe line behind the grip, and also the stamp struck TWO times under the butt right over the plug for the rod.
IMG_2789.jpg
IMG_2790.jpg