FWeaponConditionJamXX

These game settings control the chance that your weapon will jam when you try to fire it. When a weapon jams, the animation for a reload jam will play and your gun will not fire. There are 10 game settings that control the chance for your weapon to jam based on its condition.

Note that, as of time of writing, there is a bug that impacts assault rifle class weapons related to jamming. It is explained later in this article.

Game Settings

There are 10 game settings to control the chance a weapon will jam. The one that is chosen depends on the quality of the weapon being fired.

Setting	Condition Range
fWeaponConditionJam1	0%-10%
fWeaponConditionJam2	10%-20%
fWeaponConditionJam3	20%-30%
fWeaponConditionJam4	30%-40%
fWeaponConditionJam5	40%-50%
fWeaponConditionJam6	50%-60%
fWeaponConditionJam7	60%-70%
fWeaponConditionJam8	70%-80%
fWeaponConditionJam9	80%-90%
fWeaponConditionJam10	90%-100%

Behavior outside VATS mode

Non automatics

Each time you try to fire, there is a chance the gun will jam instead of firing. Non automatics includes things like the fatboy, missile launcher, pistols, sniper rifle, laser/plasma rifle, and etc.

Automatics

For automatic weapons, jamming works counter-intuitively. The chance to jam is checked only when the fire button is initially pressed. If the check passes, you can hold down the fire button indefinitely and your weapon will never jam, no matter how high the jam chance is set to. To be specific, the chance for a weapon to jam is checked only when the fire button is first pressed and not when each bullet is fired. I tested this with an assault rifle and the minigun. With a jam chance of .75%, simply hold down the fire button. The weapons will jam a lot at first, but once they start firing, you can continue to fire indefinitely without jamming, even if you reload, as long as you keep the fire button held down.

Jamming bug with automatic rifles

With an assault rifle, if you try to fire one bullet at a time by pressing and releasing the fire button, if the gun jams, your character will try to unjam the gun over and over again forever until you start holding down the fire button and the gun eventually fires.

Behavior inside VATS mode

Non automatic

Works the same as outside of VATS mode. Each shot made in VATS mode has a chance to jam. If your gun jams, you will try to unjam it until it fires. If you spend AP to fire two shots of your pistol, you normally will fire 2 shots. This is good.

Automatics

Fortunately, automatics work much better with jamming in VATS mode. Automatic assault rifles are fired in 3 round bursts. At the start of the burst, there is a chance to jam. Once the gun starts firing, it will fire 3 bullets successfully. Each burst has its own jam check. Like non automatics, if you spend AP to fire 3 bursts, you should* fire 3 shots. For the minigun, the jam check is also made when you start firing, and once the bullets fly they won't be interrupted. Like assault rifles, the minigun fires in bursts, and each burst has its own jamming check. This is also good.

Notes about jamming and VATS mode

It seems that there may be some kind of timeout period that will kick you out of VATS early, before you successfully complete all the shots you tried to execute. It may be related to the length of time spent in VATS. With a jam chance of 1 (every shot will jam) a minigun will time out of VATS in 5ish shots while the 12mm pistol will time out in about 15 shots.