Is there a certain proofing for certain gauges?
For example I have a 10ga that is proofed to 1200bar. Is this standard?

Karl.

Per my converter, your 10 ga is proofed at 17,404.53 PSI which is a lot of pressure in a shotgun if my memory serves me correcly. Here's a weblink that might help you with deciphering the proof marks of that big honking Zabala :

The Spanish Side by Side - Pressure Proof Marks



Don