Player > Feats > Fusillade
You use your numerous limbs to lay down a hail of fire.
Base attack bonus +1, four or more arms.
As a full attack when you are wielding four or more identical small arms, you can fire them all simultaneously to duplicate the effects of an automatic weapon. You use all of the ammunition in all the small arms used, and you treat this as an attack in automatic mode. Add all the ammunition expended from all of your small arms when determining the maximum number of creatures you can hit.