Its a Vello dog type revolver with a folding trigger.
I just listed one forsale in the EE tho mines is a little better condition.
You will see them on GB in the US alot.
There hard to find with Pre 1898 Proofmarks tho so hard to get Antique status as they made Millions of them right up into the 1930s
Good thing is most are Metric Calibers.