The warded creature gains a +4 deflection bonus to AC against firearm and ranged attacks, with an additional +1 to the bonus for every five caster levels you have (to a maximum of +8 at 20th level). Though the spell is called bullet shield, it also grants this protection from attacks made from firearms with the scatter weapon quality.
Section 15: Copyright Notice – Pathfinder Roleplaying Game Ultimate Combat
Pathfinder Roleplaying Game Ultimate Combat. © 2011, Paizo Publishing, LLC; Authors: Jason Bulmahn, Tim Hitchcock, Colin McComb, Rob McCreary, Jason Nelson, Stephen Radney-MacFarland, Sean K Reynolds, Owen K.C. Stephens, and Russ Taylor.