Okay, so I'm doing "When Freedom Calls" and I got the power armor and core on the roof, put the core into the armor and then picked up the minigun. Great! Except I must be doing something wrong because the damn minigun will NOT fire!

hmmm someone on my friends list had the same problem, all he did was kept trying. He died a few times then it started working. Bug maybe? I would test it while out of combat. The barrel will spin up before it starts shooting.

I both hate and love that.

Keep in mind you have to hold the fire button down for a bit - the minigun will spin up before it starts firing.

For a minigun to have the fire rate it does the barrel has to spin at a specific speed. So the gun has to start to spin until it is going fast enough. Then it will fire. Just hold the fire button long enough and when the rps are reached it will start to fire. Most games have some real life aspects to the weapons they use. Look up how they work in real life may help with some questions in game.