Honestly we had some guys here in Ontario rig up an M203 with a Madbull shell and launch it out of an M203. It functioned beyond expectations and was really fuckin' cool.
But I would say these things are pretty dangerous to use unless it was a controlled environment or someone who is specifically trained to use these. There is a lot of risk launching a quarter/half pound object at a hundred feet per second
For an idea of what we are dealing with watch the link I included below. The force that thing has at launch is enough to seriously injure or kill someone. Being on the receiving end of it and taking it in the head would probably suck a lot and be a no duff generator.
I don't want to be a buzzkill because I would get an instant MILSIM hard on launching smoke 100-200 feet away into enemy positions, but these things have obvious safety issues that would make it difficult to put into the hands of a vast majority of players.
Airsoft M203 Smoke Round - YouTube