Since it seems a few guys here like SS magazine, on the new issue, on the cover, there is a photo of two William & Son 20 gauges.
Off to the right there is what looks to be some kind of cap with threads in the middle with brass pins that have a machined flat with numbers stamped on them.
What the heck is that?

Went to lunch with a friend, the magazine was sitting on the seat and I asked him what he thought it was.
Got on his cell and called Ed Carrol, one of the editors.
During a driven hunt in England, they use it to pick your stand number.
Ed said he's gotten 10 calls already about it.