Metal gauge/armourers tool but what for?

[Damien Horn]

Hi Guys,
I have recently picked up a few strange "tools", and I am unsure of what exactly they are for or from, I have posted the first on here for you to see, and to see what you are able to tell me about it. It is 11.5cm in diameter, with the central hole being approximately 4cm diameter.It has a thickness of just under 10mm. The markings are 492 followed by a "V" in a circle and then a waffenampt with Wa637 under it. There is a letter "C" also stamped into it at the 12 o'clock position. I have a vague idea, but would not commit myself and would welcome any suggestions from those in the know. If anyone does have an idea could you please email me at damienhorn@jerseymail.co.uk
I look forward to hearing from you all shortly.
Damien
In the real Jersey,
Jersey,
Channel Islands.

[TactAdv]

You're in the Channels, Right?? It appears to be crimp gauge for a 40mm Bofors L/60 AA cannon 40x311R round. Such things are common and are used to slip over the case crimp on the projectile to check the integrity of the factory crimp before clipping up. The Bofors gun required case crimps of unusual quality, lest the gun jam on loading if the projo was moved.

US and Commonwealth crimp gauges appear nearly identical.

I know the Germans appropriated numerous L/60s from France, and I would guess that maybe if you got some of them installed there as FLAK defense, the tools might have been left around.