[Veeb]

I'm unclear about the real meaning of some of the proof marks found on, especially, old Webley military revolvers. For example, the nitro powder proof marks. What did such a mark really denote? What did the proof testing entail? I mean, did they fire six nitro powder rounds and give it the stamp if the gun didn't blow up? Did they fire a hundred? I'd be interested in any history or other info on this.