Listen, Captain America, the good guy doesn't always win.
Sometimes the best you can do is loose as slowly as possible.
The fact of the mater is, facing 7 people at once, even a submachinegun may not be enough.
Have fun with this new and exciting "how a middle aged Rambo defeats more than a half dozen imaginary foes" thread.
All you can do is train for the worst and fight like you mean it.
This puts me in mind of one of the points I posted in another thread.
Bring a friend. Have him bring his rifle.
Stopping power: The power some guns have to make you stop what you are doing and get your wallet out.