Grenade (Frag)

Fragmentation Grenade is an explosive thrown weapon that appears in all Fallout games.

Fallout and Fallout 2
Fallout and Fallout 2 Standard Fragmentation Grenade. Most effective when used on groups. 

Fallout Tactics
Fallout Tactics Standard Fragmentation Grenade. Most effective when used on groups.

Note
Frag Grenade is primary weapon for grenadier character throughout most of game. Decent damage, and abundance allow it to be used often and indiscriminately. However, it`s recommended to have a sniper character ready to provide cover and long range support, since the AP cost of throw is quite high.

Fallout 3
The Frag Grenade is the first type of grenade you'll find in the game (check the first blue Mailbox as you come into Springvale from Vault 101) and is commonly carried and used by melee equipped raiders and super mutants. While it's unlikely to kill you by itself it can do a lot of damage in one hit and has a high chance to cripple arms and legs. Its blast radius is small compared to grenades you'll get access to later (such as the nuka grenade or plasma grenade) but it can still be useful against multiple attackers if they're bunched together at a pinch point like a stairwell or doorway.

The in game physics for grenades are quite realistic which means throwing "up" a stairwell or hill means they'll most likely just coming rolling back before detonating next to you. The plus side is you can throw them through doorways or bounce them around corners to attack enemies you can't see. Be careful trying to throw them through windows though as, if they hit anything they'll bounce back at you.

The Frag Grenade appears to be based on the Danish Håndbombe M/23, only it has grooves (ala the Mk 2) on the middle of it.

Are You John Rambo?
A sapper, a demolitions expert. If you take all three ranks for a combined 60% dmg bonus and max out your explosives skill, frag grenades become more than just firecrackers. You'll be able to kill nearly everything with a single grenade. Simple frags become super mutant kryptonite exploding in a ten foot radius for 162 damage! That's enough to outright kill regular super mutants, sometimes in groups of two or three, like when they're grouped behind sandbags. The wasteland's toughest enemies, deathclaws, super mutant brutes and masters end up gimped (multiple crippled limbs) after one blast, so you can easily finish them off with small arms fire. Crouching and questing for the wired reflexes perk are the only known ways to increase VATS grenade range as gunslinger and commando perk benefits don't seem to apply. Tap Outcast leader Casdin for the The Outcast Collection Agent side quest if you're going to be a pull-the-pin-with-your-teeth styled Rambo character, you can buy cheap, nearly broken energy weapons and power armors, then trade them in for tons of grenades at a significantly reduced cost.

Defensive Strategies

 * You'll know a grenade has been thrown at you when you see a red circle with a pointer appear at the center of the screen. Your best bet is to run quickly away to get clear of the blast radius.  Ducking behind cover isn't always reliable as the grenade can roll past your cover and detonate right next to you.


 * If you see an enemy with a grenade in their hand you can target the grenade in VATS just like any other weapon. If you hit the grenade it will detonate and damage whoever was holding it. Even if the grenade isn't in the enemy's hand, like if you sneak up on an opponent with grenades holstered, you can still target and shoot them while on the belt. Sadly, you do not receive experience for these types of sinister trick-shots.


 * shooting grenades in an enemy's hand seems to have an unusually high success rate. multiple times on the X360 version, players have shot at various grenades-in-hand with only about 15-20% chance to hit & been incredibly successful.


 * Grenades may also be shot while mid-air as VATS recognizes them as a separate targets. This is extremely useful to protect friendlies who may be easily injured or killed otherwise.

Offensive Strategies

 * Frag Grenades in Fallout 3, despite their pineapple textured artwork, and what their name implies (frag as in fragmentation) don't actually send out any shrapnel. Instead they behave exactly like concussion grenades, anti-personnel devices designed to cause damage with explosive power alone. Therefore they are especially effective in enclosed areas or close-range combat because of their minimized friendly fire risk (no shrapnel spray coming back at you).


 * They work at closer ranges than you might think, with an in game blast radius of about 10 feet you can safely bomb enemies as close as 11 feet away! Plasma and nuka grenades have almost double the blast radius, beware.


 * Fallout 3 frags have a small blast radius so anything you can do to get the enemy bunched together by leading them to doors, hallways, stairwells or other pinch points will increase their effectiveness. Just remember to be wary about trying to throw upwards. It is easier to roll a grenade down a staircase than it is to toss one up.


 * Grenades have a random chance to knock down opponents, and flip radscorpions upside down. The player can then switch to a firearm and hose down the helpless target.


 * The distance the grenade is thrown depends on how long you hold the trigger. Don't just tap it unless you want it relatively close to you. Grenades cannot detonate in your hand, the player does not have the option of cooking a grenade in real-time (VATS only). When holding down the trigger on a grenade, the player is winding up for a long throw with the pin-out, and the safety lever held down.


 * Explosions from grenades that land and roll typically result in single or double critical limb damage to the legs as the explosion comes from the ground up. Instant detonations are usually mid-air upper body impacts and typically cripple the head and arms.


 * Grenades have a low (24 AP) action point cost for the damage (162max) they do, but throwing them outside of VATS then following up in VATS with aimed-shots at their crippled limbs is an effective alternative against groups or big "nasties". Note: crippled limbs take double damage, and most headshots are double damage by default; making it possible to achieve an (x4 dmg) attack.


 * Using a frag grenade on any enemy that can be frenzied (such as robots, or giant ants) has a relatively high chance of triggering it. Fire ants are especially susceptible to causing riots among themselves, as they have a ranged attack.


 * "Dynamite fishing" is a term for using explosives to net fish; when deployed underwater explosives create a deadly underwater pressure wave. Known as depth charges to the military, the effect works with the Fallout 3 physics engine. Grenades are already an especially excellent tactic against Mirelurks, either killing or crippling the creatures instantly, they also have a hidden in-game bonus. It's almost impossible to miss! When grenades hit the water they get trapped a few feet under the surface right next to their intended victims. There's also a very satisfying water plume styled explosion!


 * Since the player takes only a fraction of normal damage while in VATS mode, all kinds of grenades can be freely thrown at point blank range with little risk to the player's health. However, keep in mind that party members receive no such benefit!


 * If you're the 'stealthy' type, you can always slip a live grenade. into an unsuspecting victim's pocket. Be extra careful though; if the victim spots you they will disarm the frag, if you can get one in, then run your legs outta' there since it will create a point blank explosion.

Instant Detonations

 * During a VATS shot, the player does not have the option to aim at specific body parts. However, the player does gain the following ability: Grenades are judged to be perfectly "cooked" and will detonate instantly if you hit the target (actually connect with it). Additionally some throws that hit the ground may still detonate instantly if the grenade rolls into and touches the target. To this extent, opponents with larger bases tend to draw more instant detonations, for instance robots like the Robobrain with its large double set of tracks. On the other extreme, the floating Mister Gutsy will never cause a roll-in detonation.


 * Take note: Outside of VATS contact is meaningless, a lobbed grenade may bounce off a target as grenades explode on a timer, they are not equipped with a proximity fuse.


 * As expected with the touch-detonation system: bigger monsters and closer ranged targets end in instant detonations more frequently than smaller creatures and longer ranged targets.


 * Fast moving targets (runners) seem be better tracked by VATS and that draws a lot of instant detonations too.


 * It should be noted that even on a 95% calculated VATS shot long-range throws rarely touch the target, however they usually land quite near, exploding a split-second later, often still doing full damage (except, as pointed out before, in steep terrain like a balcony, fire escape, cliff, or rooftop).


 * After maxing out explosives skill, grenade range can be extended quite a bit if you take advantage of the grenade's tendency to roll. Long range VATS shots of 65-75% will almost perfectly roll-in and detonate right at an opponent's feet. The experience is different if you haven't maxed your skills because your percentage sweet-spot won't be at the same distance as the grenade's arc.

Traps

 * It is common to find several grenades hanging on a string from the ceiling. These are called a grenade bouquet and will be activated with a tripwire and will explode on a timer. The bundle of grenades can be disarmed with a high enough explosives skill or can be shot down (this will cause them to explode). If you do accidently activate the tripwire try to run out the area as the grenades are on a timer. Note that these grenades won't show up as red arrows.

Bugs

 * The "Rocket-Boots-Bug": there's a semi-common bug with deathclaws, behemoths and giant radscorpions. The explosion may launch them into the sky, which is fine, if a bit comical, but can lead to multiple queued VATS shots wasting grenades and AP (exploding harmlessly under them). It's probably best to setup one targeted throw at a time. Or use the more common approach to fighting "big nasties": one grenade to cripple it then mop-up with small arms fire.


 * Destroyed grenades i.e targeted in VATS and shot out opponents hand, have a condition of zero yet you can use other broken grenades to fix them thus restoring its firepower.


 * When a missile launcher is broken from launching a missile, if you have one grenade/mine of any particular type in your inventory, e.g. having one frag grenade but any number of other grenade/mine types, and it is the next weapon you equip, you will have unlimited ammo for that particular grenade/mine until it is unequiped. The next grenade/mine thrown after the first will be invisible while held in the player's hand but will appear once thrown. This is an excellent way of obtaining many bottlecap mines as they can be disarmed and picked up, adding them to your inventory to be used at any time. VATS, unfortunately, cannot be used until the grenade is unequiped.

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