This chart is in one, compare as the best of my knowledge, please correct me if mistaking or missing, thanks!
*WG, ASG, Umarex, Rhino & KWA are all full metal structures (not the Umarex R8, the only plastic body in the list), I would say pretty solid and durable, they all metal shells models available in Canadian stores. The others models particularly Japanese models they are rare and hard to get in Canada.
All the above models their trigger pull are so stiff out from the box, if you know how to tune it smooth, that would have a smoother trigger pull and last longer. Minimize the wear and tear a lot!
Japanese made revolvers, very nice built in finishing and good for collection, most are in plastic body with metal internals, recommended using 134a gas, some are gas in grip, metal shells that shoot one bb each, Marushin is one of it. Other models gas in cylinder and shoot 12-24 rds with no shells, Tanaka is the one. They are light weight mostly and fragile, not durable and don?t last long, no parts support mostly. If you are using green gas or propane, that even shorten the life time and easy to get gas leak.
Below two pictures are Japanese models:
**pictures are from website/FB
Using CO2 is more power and shoots loud, cartridge is stored inside grip, you may modify adapter to connect with HPA or CO2 tank. Using green gas one is less power and shoots like fart, gas also store in grip on most of the models, but Japanese has Pegusus model also, store 134a gas inside cylinder, load 10-24 bbs in cylinder with no shells reloading needed.
Picture from Octagon Airsoft in HK, King Arms gas and CO2 revolver series, using shell .