First, what you might want to do, is make it so your character will always face up. There may be multiple ways you can do this. I usually go to the characters section and make it so that the character only has it's up frames. Doing this will make the character always face upwards.
Second, it's not enough to just leave your character with up frames, you'll have to make it so your character shoots in that direction as well. Here's how it's done.
*Go to input scripts. Double click the control for "Use Item" so that you open the scripting window.
*Disconnect the comparison branches (Entitled "uses ammo?" and "needs reloading?") from "the Start/Stop Using Equipment" event.
*Select either the"uses ammo?" or "needs reloading?" event, doesn't matter which one. Put in a "Change Facing Direction" event. Set the direction to up.
*Connect the other comparison branch (The one you didn't select) to the top of the "Change Facing Direction" event, so that the "uses ammo?" and "needs reloading?" events are both attached.
*Connect the bottom part of the "Change Facing Direction" event to the "Start/Stop Using Equipment" event.
The scripting before
The scripting after
And your done! Please let me know if you found this helpful. I know it was pretty detailed, but I figured that I might do that in case there were some people who would need that kind of instruction.