Fallout 4: VATS

Using V.A.T.S., AP Costs, and Weapon Modifications

The Vault-Tec Asssited Targeting System, or V.A.T.S., allows Fallout 4 players to slow time and target specific enemy body parts. The amount one can use this feature is based on AP, or Action Points. AP are raised by having a higher agility rating (+10 per point), and armor mods that increase AP. In this guide to VATS, we'll cover usage of the system, and get into weapon types and modifications and how they affect the AP Cost of each shot in VATS.

V.A.T.S. Basics

About V.A.T.S.
Playstation 4 and Xbox One users both press the L1 (or LB) button to go into V.A.T.S., while PC players press 'Q' (this can be changed). While in V.A.T.S., time seems to slow to about 5% of normal, meaning you're not invulnerable but not going to get hit as often while you seek targets. You are able to select different body parts to attack while in VATS, and when done the character will fire off the string of shots. While in V.A.T.S., you can select to aim for head shots - which typically do double damage on humanoids, though various enemies have different weak points (Deathclaws' is the belly, but it's hard to hit). These are good for fast kills, but sometimes it's better to cripple a limb in a longer fight. For weaker monsters, you'll often kill them before you can cripple a limb, but enemies with high life may have limbs weaker than their total health pool.

Players executing moves in VATS take 95% reduced damage, so higher agility builds will be able to make up for possible weakness by spending more time using this mode of combat. Those who have Action Boy and Action Girl will be able to use VATS 25/50% more often than those who do not use those Perks. This is only after you've hit the execute button and can be seen when you fire a fat man at a nearby target, as you should benefit from the reduction. The damage resistance that VATS provides is huge, so VATS builds have definite strengths and also allow players who are not good at shooters to excel at Fallout 4 despite its heavy gunplay.

Melee and VATS
Melee players still benefit from VATS due to the fact that it's the only way they can benefit from critical hits, while also giving them time to queue up attacks on multiple opponents with the slowed time benefit allowing them to perform superhuman feats, so long as targets are in range.

With the Blitz Perk, this becomes less of an issue. Sneaky characters would be especially foolish to pass up VATS usage, because you can crit on a sneak attack along with Agility's Blitz Perk, which will let you deal even more damage - with Blitz that base damage gets multiplied by the distance, then sneak attack and crit bonuses for massive damage. Yeah - I love that Perk and have to recommend it even out of context. Blitz is almost essential for melee users, very hard to pass up that amp'd damage and VATS distance, allowing you to close gaps instantly.

Critical Hits
Critical Hits are now used solely in V.A.T.S. and are controlled by the player. As your critical meter builds, you're able to use the shot at will by pressing the jump button just before the shot is taken in VATS. With Critical Banker, you can store more than one Critical Hit. At 10 luck, you can expect it to take about 5 hits to build the meter to full. The rate the meter builds is based on the character's luck and certain unique bonuses that can be found on weapons. The amount of damage a weapon will do on a critical hit is based upon the weapon type - sniper rifles will do more crit damage than a pipe pistol.

Crippling Limbs
Different parts of the body being crippled have different effects on various creatures. The below list is for a human, there are many creatures in the wasteland. A Radscorpion's tail being crippled may prevent it from stinging you, a Deathclaw cannot perform its leap attack with a crippled leg. Enemies that are melee in general will have a harder time reaching you with crippled legs. Crippled heads won't have a noticeable impact on many enemies, it's just for more damage. On many enemies, it may impact Perception and allow you to slip away when sneaking. Note that if the bar is depleted, the limb is already crippled. Most enemies will display an animation when this happens. You may want to switch to another, or else fire as you were and reduce their HP to kill them.

• Crippled Head - Rarely happens, but should impact perception and reduce aim of ranged opponents. Additionally, it will let you sneak away easier if you've reason to do so.
• Crippled Armos - A crippled arm will reduce aim, for sure. Enemies may have an arm completely taken off, which obviously affects them in a very negative way.
• Crippled Leg - Reduced movement speed, and sometimes humanoids who lose legs can only lie there and await their death. For a big enemy like a deathclaw, you're not likely to see this happen but rather experience it continually limping toward you.

For the player, a Stimpak will heal a crippled limb.

VATS, Weapon Modifications, and AP Cost per Shot

While I don't have an easy way to get exact numbers on AP from a single shot, I have some good observations for you that may impact your decision-making when modifying weapons. If you're a heavy V.A.T.S. user, with plenty of Agility and Perception, you can certainly benefit from this information. Certain parts of a weapon will greatly impact its AP usage. First - Rate of Fire is a big indicator of how many shots you can get off in VATS, although it's not the be-all-end-all. For automatic weapons, rate of fire will increase the amount of bullets/lasers per burst, while on a normal gun it is for single shots. The higher, the better, in most cases. The Weapon Type plays the single biggest role on AP cost, but we can reduce this AP cost - sometimes at the expense of other stats, particularly range/accuracy in a number of ways. You usually do not have to sacrifice damage, just your chance to hit from large ranges.

• Receivers - Receivers can greatly impact the rate of fire, a receiver that is not automatic yet says it increases the rate of fire, light, or has a hair trigger, is going to let you reduce AP cost in VATS. Changing to automatic, your weapon will consume more AP but fire in bursts at a cost of reduced accuracy and range. I generally prefer powerful single shots, because these conserve ammo, but that is entirely up to you. The higher a weapon's rate of fire the more mods like hair trigger are going to boost its rate of fire. For a slower weapon, it's not a great impact on the number of shots in one round of V.A.T.S. Mods that say heavy or increase damage, aside from the really advanced ones, raise AP cost. You need high Gun Nut or Science to make a weapon do high damage AND be low AP.
• Barrel - Shorter barrels lower AP cost in VATS, for whatever reason. If you're using a combat rifle up close a lot, then consider switching to a short light or short ported barrel as opposed to the normal short barrel because these will improve your own accuracy by reducing recoil when firing the weapon manually. Longer barrels increase the effective range of a weapon, allowing you to hit targets further. Outside that range, even high perception won't help - I consider range to be more important than accuracy, and a long barrel doesn't hurt AP cost as much as a scope. My testing showed that from the same spot, having a higher range and lower accuracy was better, and I got 2 more shots in VATS - so if you must go for range but want the most hits, go for the long barrel!
• Stock - Some weapons can go from pistol to rifle by changing the stock, although this is a bit rare and generally for some energy weapons (laser rifle/pistol). A shorter stock reduces AP usage in VATS, but gives you more recoil (harder to aim subsequent shots) with the weapon when firing manually. This makes sense from an AP usage perspective - if the stock is long, the character is going to use it, shoulder it, and fire. A short stock is going to be lighter and faster to shoulder and aim. Notably, a shorter stock WILL NOT change your hit rate in VATS, but reduces the AP cost to fire - so it should be the first thing to go if you would like to get an extra shot out of your sniper rifle. Now, for handguns, marksman's grip is going to give you a slightly lower AP cost - maybe not enough to make an extra shot, but your meter will not be fully depleted so you can take your next much sooner..
• Magazine - This has no effect on VATS AP usage as far as shots you can make at full, although a slow reload/high cap weapon is going to be reloaded in VATS and take more points to do so. Faster reload will use less. Having a higher capacity and faster reload usually has to be balanced, until you get to the high level mods that do both. Normally, I'd prefer a higher capacity because I can reload during downtime or repositioning, and later get the combo effect.
• Sights and Scopes - Having a normal sight is a big no-no. Presumably, it takes your character longer to aim, so increases the AP cost by a little bit. A reflex sight is going to reduce the AP cost to fire the weapon in VATS. Now, with regard to scopes, they pretty much double AP usage if you use a long scope but greatly increase accuracy, which is used along with line of sight and range in VATS to determine hit rate. Medium and short scopes have smaller increases to AP usage, so consider using these instead if you've got high Perception. For people who like to tweak, you might find you have 3 shots with some left over with a short scope. You could get a bit more accuracy by switching to a medium scope while still being able to take 3 initial sniper shots.
• Muzzles - Muzzles do not impact the AP cost of shots in VATS, even on energy weapons. These are for your use when aiming manually, although some might impact accuracy at the reduction of range. Bayonets are junk, but muzzle brakes and compensators may come in handy if you fire your weapon manually a lot. This is going to keep your aim on target without the weapon drifting upward so much (recoil). Your manual aim will be better, though you'll sacrifice a little bit of accuracy in VATS.

Mod Those Weapons!
I did a lot of testing to come up with this info, so I hope it's helpful to some of you when it comes time to tweak your weapons. For me, this means an extra shot out of my sniper rifle in VATS by reducing the size of the stock and changing the scope to small. A scope-less sniper rifle becomes a hunting rifle, but it's just a name. I have high Perception, so the scope size reduction doesn't hurt me much. I hate aiming manually with scopes, and would rather use the AP in VATS rather than holding my breath - but your accuracy is sometimes higher than that of VATS if you're good with controls. Regardless, knowing how these things affect AP usage in VATS may help you test and tweak your weapons so that you can get maximum efficiency out of them.

Example Articles for Tuning Weapons:
I've started a series on tuning weapons for AP usage in VATS, or else to make them good without VATS in mind. Take a look at:

• Sniper Rifle from Hunting Rifle: 2 Examples: This page looks at making two very differnt weapons out of one Hunting Rifle, with only Gun Nut rank 1 required.