Goto Atlus America

Combat Range / Placement Charts
Positioning Hand Firearm
Main has limited combat range, but very good firearm range. His best placement is up at the front of your party, on either the right or left side.
Positioning Hand Firearm
Put Mary in the very back of your party to make the most of her. Her gun is really of little use, and her weapons and Persona ranges are usually very far.
Positioning Hand Firearm
Brad is very well off range-wise. Put him to either side in the second row, or dead center in the third row.
Positioning Hand Firearm
My recommendation for Nate is second row center. This will get him close enough to give him somewhat of a hand-combat area. His firearm range, obviously, is of no concern.
Positioning Hand Firearm
The only character more lacking in range is Chris. Mark works best at the very front of your party, right in the center. In any other place, he will lose some of what little coverage area he has.
Positioning Hand Firearm
Ellen is in the same position as Main. If you have her in your party, place her up at the front, on either side of Mark.
Positioning Hand Firearm
If you have Alana, either put her where you would put Ellen, or somewhere in the second row. Her firearm doesn't have good range, but long-range combat isn't one of her specialties.
Positioning Hand Firearm
While Yuki is in your party, set her to one side of the middle of the second row, and Nate on the other. This will give her some range for her firearm, and maximize her weapon combat area.
Positioning Hand Firearm
Chris is very, very limited in range. Unless you plan to rely only on his Personas, keep him in the very front in the middle.