The patent date is probably close to the time it was manufactured.
It has the transitional fill cap that was the early 9/16" size, but with coarse threads. Most all 9/16" fillers were fine machined threads. Later 13/16" fillers were coarse, pressed threads.
I have only seen this transitional filler on the Junior Dash Lamps and one King Fire lantern.
The Paull's Leaders of the same time period had a 5/8" coarse thread filler.