Weapon Jams

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Weapon Jams[edit | edit source]

Many weapons in RogueTech have a jamming mechanic and you might have come here looking for how to Mitigate with Gunnery and Recoil Reduction, or perhaps to understand how those interact. No one wants their primary weapon jammed in a critical situation! Most of this will be common sense after reading the weapon descriptions or the wiki page for it; but perhaps you want to know more.

Note that this article is posted circa 'Project B' RT which introduced major feature changes following the release of Urban Warfare. The mechanic itself is unlikely to change much going forward as it appears stable. Individual weapons stats, including any examples used, are subject to change between patches of course.

Skip to "I want to know more" if you want high density formula and game mechanics; however this is really not needed beyond the information already available to the player for the purpose of game decision making. For the curious.

What determines whether a weapon jams?[edit | edit source]

Bonuses and Attributes displayed in-game can give you the basic information needed here; but the wiki for each weapon has additional data that is helpful. On the face of it are Flat and Recoil modifiers, with different mitigating factors for each.

Let's take an example crowd favorite Weapons/Ballistic/Ultra_AC20_(C) and look at the stats.

Bonuses and attributes[edit | edit source]

These are displayed in game and never mean anything other than what they say. Never assume an interaction or apply fluff text to imagined game mechanics!

For the example UAC/20(c)

  • This weapon has a recoil of 4
  • Weapon has a jam chance of Recoil X 4 - mitigated by Gunnery and Recoil Reduction
  • Weapon has a flat 32% jam chance - mitigated by Gunnery
  • Ultra Autocannons have select-fire of 1 or 2 shots

From this you would see that this weapon has a high Refire Modifier (recoil) of 4 and a fairly high base jam chance of 32%! It should be understood that this refers to firing in 2x mode, as you can find from further inspection that it defaults to this. Other weapons might have only a flat jam chance, or only recoil related jam chances.

Firing modes[edit | edit source]

These are generally described well by the weapon text; however you may need to experiment to see how each behaves or check the wiki if you want to be sure. For the purposes of this discussion, we're interested in base jam chance by Gunnery skill and also the default firing mode and recoil in case it wasn't clear from the attributes text.

Our example UAC/20(c) has a table at the bottom of it's wiki page as follows:

Damage Per salvo Modifiers Range Chance to jam at gunnery skill level(%) Other effects
Mode Default Ammo Norm Heat Stab Rounds Projectiles Heat Recoil Accuracy Evasion ignored Crit Chance Falloff TAC Min Short Medium Long Max 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
x1 UAC20 100 0 25 1 1 20 2 0 0 0.50 0 120 210 300 360 36 30 25 20 14 9 3 2 2 1 0 0 0 0 0
x2 UAC20 100 0 25 2 2 40 4 0 0 0.50 0 120 210 300 360 56 49 41 33 24 15 6 5 3 2 0 0 0 0 0

NOTE that this is DIFFERENT for each jammable weapon in the game!

Crit state[edit | edit source]

Seriously, why are you continuing to fire a damaged weapon? Many weapons with jam mechanics also have destructive explosions attached to them. Usually you will see some text indicating self damage on jam, in which case the %chance of it is somewhat irrelevant as the weapon may completely destroy itself if fired again in an already critically damaged state. This is permanent unless an edge case where the weapon in question is also integral to a mech and repairable even if destroyed.

Penalties do not combine[edit | edit source]

Remember how it was noted above that attributes are never to be interpreted as anything other than 'as written'? This means that if there are two causes for possible jam, each is discrete and standalone.

Flat jam chance and recoil related jam chances are rolled separately, not multiplicative, additive, or otherwise interactive.

Mitigation[edit | edit source]

Recoil[edit | edit source]

Gunnery has -1 recoil bonus at skill levels 6 and -2 bonus (not cumulative) at skill 9. FCS variants, some weapon mounts, and other unique items can all reduce recoil. This should be a pretty obvious game mechanic so no need for more detail.

Gunnery skill[edit | edit source]

Gunnery can be increased with battle computers and other support equipment, or through the usual way of increasing a mechwarrior's XP. It's notable that the table goes up to 15, where the max innate skill a mechwarrior can have is 10. This may make it impossible for an unaugmented mechwarrior to completely mitigate jam chance with some weapons.

Unjamming[edit | edit source]

Weapons do not unjam based on a timer; rather it is a Gunnery skill check each turn. Strictly, if you were very unlucky, an entire mission could go by without a weapon unjamming. This is an unmodified roll based on your Gunnery skill, so the higher the better. A random number generated from 1-10 is compared to your Gunnery skill. If the number is LESS than your skill, then the check passes. The roll is made at the end of the initiative phase. Pilot skill rolls work very similarly.

Example[edit | edit source]

So let's use this information above to find the jam chance for an example Dekker with Gunnery 5 who fired his UAC/20(c) last turn in mode x2 and now wants to fire again without waiting. The game shows a refire modifier of 4 because he has no skill or hardware helping out here. For a weapon with no jam mechanic, this would simply mean he has a +4 to-hit penalty; however, in this case, it could contribute to a jam!

4x4=16% chance of recoil related jam.  If this passes, then:
24% chance of jam related to firing the weapon in x2 mode per lookup table unique to the UAC/20(c).

Maybe Dekker is better prepared next drop and has Gunnery skill 6 and a FCS Recoil installed in his cockpit. Now, after firing he has a refire modifier of 1, for +1 to-hit and hopefully less chance of jamming.

4x1=4% chance of recoil related  jam.  If this passes, then:
15% chance of jam related to firing the weapon in x2 mode per lookup table unique to UAC/20(c).

For our example Dekker, having a Gunnery skill of 5, that means approx 50% chance of unjamming on a given turn. Pilots with a Gunnery skill of 10 would always unjam after only 1 turn of nonfunction.

I want to know more[edit | edit source]

In practice, it should be 'enough information to have as high gunnery as possible and to assure mitigation of all recoil, or expect a high jam chance. Please do NOT engage the RT support team with questions at this level of detail unless you're very sure of a bug or are very sure you know what is going on and have a contextual query specific to RT. Mere curiosity is below the threshold of support, as is coding tutorial. This is noted because, while RT uses CAC/WR and other tools they are used in other mods and are a community resource. If you're looking for exactly where that line in the sand is, continue.

This mechanic is controlled by CustomAmmoCategories.dll; but is based on WeaponRealizer.dll, and there may be mechanics that utilize both or others. In WR-Readme.md we find the following stub text that a modder could find useful::

* Refire Modifier crit multiplication - weapons can now have a bigger refire penalty when damaged (critted); see setting `damagedWeaponRefireModifierMultiplier`
* Weapon Jamming - weapons with weapon defs tagged `wr-jammable_weapon` can jam, based on refire modifier and `jamChanceMultiplier`/`wr-jam_chance_multiplier-X`; `X` multiplies the refire modifier to determine a percent chance of jamming happening; Rolls against gunnery skill to save vs. jam and unjam are preformed.

Additionally, in Readme.txt for CAC we find:

"DamageOnJamming": true/false, - if true on jamming weapon will be damaged
"DestroyOnJamming": true/false, - if true on jamming weapon will be destroyed (need DamageOnJamming to be set true also)
"FlatJammingChance": 1.0, - Chance of jamming weapon after fire. 1.0 is jamm always. Unjamming logic implemented as in WeaponRealizer
NOTE! There FlatJammingChance can be altered via CACFlatJammingChance statistic value per actor's and/or per weapon's statistic collections
"GunneryJammingBase": 5, - 
"GunneryJammingMult": 0.05, - this values uses to alter flat jamming chance by pilot skills formula effective jamming chance = FlatJammingChance + (GunneryJammingBase - Pilot Gunnery)* GunneryJammingMult
if FlatJammingChance = 1.0, GunneryJammingBase = 6, GunneryJammingMult = 0.1, GunnerySkill = 10
result = 1.0 + (6-10)*0.1 = 0.6
GunneryJammingBase if ommited in weapon def., ammo def. and mode def. assumed as 5. 

How could I use this information?[edit | edit source]

If you're looking to modify or create weapondef using this mechanic, it is notable then that lower GunneryJammingMulti equate to a lower impact of skill on the resulting jam chance, though you wouldn't want to use very large values to move this around. Further note that this is NOT the final jam chance presented to the player, though it is close. You'd have to dig in to jamm(abstractactor) in the cac codebase to fully tease it out, but these are the external levers available to balance with.

Example (note order of operations adherence): Gunneryskill=5,FlatJammingChance=.32, GunneryJammingBase = 3, and GunneryJammingMulti=.08


Gunneryskill=5,FlatJammingChance=.32, GunneryJammingBase = 3, and GunneryJammingMulti=.05


Further, not all weapons use the same mechanics. An example is RAC, which give the user a %/shot jam chance that is not recoil based and thusly unable to be mitigated and also has a decreasing jammingmulti as count mode increases.