That's a pretty explosion but IMO it needs to happen a lot faster than it currently is. Perhaps add a faster explosion on top of that and leave the current effect as particulate smoke from the aftermath, slowly drifting outwards?
What's the difference between Unity and Unity Pro? I've never really looked into the engine before, is it additional features? Or a royalty system?
roger that will work on the explosion. unity pro gives you profiler, dif shaders, effects, access to game engine code, render to texture, hdr, and a few other things.
once you get the pro version anything you make is 100% yours. the pro costs around 1500 dollars i think.
heres a quick first person weapon script i threw together :
