The most basic form of attack with a firearm is a single shot. One attack is one pull of the trigger and fires one bullet at one target.
A number of other feats allow a character to deal extra damage when he or she fires more than one bullet as part of a single attack at a single target. (If a character doesn’t have those feats, he or she can still fire more than one bullet—but the extra bullets don’t have any effect, and are just wasted ammunition.)
As with all forms of ranged weapons, attacking with a firearm while within a threatened square provokes an attack of opportunity.
Because of the weapon’s unwieldy shape and size, an attacker using a longarm takes a –4 penalty on attacks against adjacent opponents.
You take a moment to line up an attack on a target. You have a +2 bonus on your next ranged firearm attack against that target. You lose this benefit if you fire at a different target than the one you originally aimed at.
Full Round Action
If a ranged weapon has an automatic rate of fire, a character may set it on autofire. Autofire affects an area and everyone in it, not a specific creature. The character targets a 10-foot-by-10-foot area and makes an attack roll with a -4 penalty; the targeted area has an effective Defense of 10. If the attack succeeds, every creature within the affected area must make a Reflex save (DC 15) or take the weapon’s damage. Autofire shoots 10 bullets, and can only be used if the weapon has 10 bullets in it.
Autofire is not the same thing as burst fire, which involves firing a short burst at a specific target. Firing a burst requires the Burst Fire feat. If a character fires a blast of automatic fire at a specific target without the Burst Fire feat, it’s treated as a standard attack. The attack, if successful, only deals normal damage—all the extra ammunition the character fired is wasted.
Some firearms—particularly machine guns—only have autofire settings and can’t normally fire single shots.
Reloading a weapon takes a certain amount of time depending on what kind of weapon it is. For weapons that use magazines, it is a move action. For most light weapons and manually loaded rifles and shotguns it takes a full round action. With manually loaded weapons, you can opt to load only one bullet or shell – this takes only a move action.
It is assumed that when reloading magazine based weapons, the character is keeping the magazine they have just replaced, whether empty or partially full. However, if you are proficient with the weapon you can perform a speed reload. This is a free action, but the replaced magazine will be dropped at your character’s feet regardless of its current capacity.
Partially filled magazines can be combined, but it takes five minutes to do so and requires the magazine to be opened up.