British Gauges from H&H

Maybe somebody can tell me what these are. The gauges are roughly 9mm so I wound up with them. The came out of the UK, reportedly from Holland & Holland (hence the H&H). Given that they are H&H, I can’t imagine that they are 9x19 related in any way…but!

Tony or John or whoever, what do you make of these?

The top gauge has a diameter of 0.3855 inch
The middle gauge has a diameter of 0.3915 inch
The bottom gauge has a diameter of 0.3635 inch

I could make some guesses on these but truly have no idea of their intended use.

What do you know!!! John Moss just called me and told me these were gauges used on an experimental H&H submachine gun in 9x19mm that was a competitor of the Sten. Reportedly it was a great gun and cost the same as only 100 Stens!!!

Well, I was on my second glass of wine so maybe that wasn’t exactly what John said…

Pistol Revolver No2 go and no go gauges ? to make sure the chambers are all within limits and one to check that the chambers have no obstruction ?