Already been made.
I do, however, it is broken.If you can find someone to get a correct script, I will gladly give you the model. Please note: The model is not accurate to the one in Fallout 3, it looks like so:I used to have it in game, but since I am terrible at scripting, I broke the script somehow and couldn't fix it.I suggest that you either edit a Rocket Launcher script to be more powerful, or edit the Mininuke script to be less powerful.
I love how much that resembles the default gun.