And some more:
This looks a bit like a Chiappa Rhino, but I'm pretty sure its just a prop. Referred to as a "modified second-series Nemex". The "cylinder" is actually a 'charge pack"
Found a promo pic that shows the Envoy Blaster's markings. "NKO ARMS"
https://images-na.ssl-images-amazon....00,999_AL_.jpg
This seems to be a custom build for the show