Weapon Cosmetic Stat Removal

Summary of the Bug

In Space Marine 2's weapon customization UI, there are two pickers per weapon: variant (gameplay) and skin (cosmetic). Internally they store separately, but both ultimately feed into the runtime's weapon resolution:

Variant pick -> loads a modificatorsGroupName. The named group in firearm_modificators_library.sso defines every stat modificator on that variant.
Skin pick -> loads a skinName. The named skin in firearm_skins_library.sso defines which mesh regions, materials, and attaching actors are used. The skin's modificatorsGroupName is NOT loaded when applied as a "skin" - only its visual definition.

When the player keeps the variant's original skin, the variant's modificators all apply correctly. When the player swaps to a different skin (whether another variant's visual, a chapter DLC like White Scars, a Hordemode reward color, or just the basic Standard Issue look), the runtime rebuilds the weapon visual. During that rebuild at least one stat type, rate of fire applied via ModificatorFireRate , is overriden and the variants stats are lost. Damage, headshot multiplier, magazine size, reserve ammo, charge duration, all survive a skin change correctly.

Weapon Stat Impacts Confirmed

Empirical confirmation from in-game testing on Melta Rifle, Multi-Melta, Stalker Bolt Rifle, Bolt Sniper Rifle, Instigator Carbine, and Plasma Incinerator:

Stat / Modificator	Outcome
`ModificatorFireRate` (barrel-tied, raw-set)	Strips
`ModificatorDamageAmount` (shell-tied)	Survives
`ModificatorHeadshotMultiplier`	Survives
`ModificatorChargeDuration` (barrel-tied, delta)	Survives
`ModificatorClipAmmo` (clip-tied, absolute set)	Survives
`ModificatorAmmoPool`	Survives
Godlike preset `descriptionOverride.barrelDescriptions.common.fireRate.shotsPerMin`	Survives (immune)
`shotsPerMin` (in base description, no modificator)	Survives (no modificator to strip)

Weapon Stat Impacts Predicted

Based on the pattern (every non-FireRate modificator tested has survived), these are predicted safe through any skin swap:

Modificator	Schema target	Used by	Prediction
`ModificatorBulletSpread`	barrel + delta	Accuracy variants (e.g. Bolt Rifle Master Crafted `02`, Salvation of Bakka, Gathalamor Relic)	Safe (delta, like charge duration)
`ModificatorRecoilRiseTimeSpeed`	barrel + delta	Same accuracy variants as above	Safe (delta)
`ModificatorReloadRate`	weapon-wide (no targeting)	Ammo Capacity variants (Bolt Rifle Ophelian Alpha `04_b`, Auto Bolt Rifle, etc.)	Safe
`ModificatorHeatPercentPerShot`	barrel + delta	Plasma weapon heat-management variants	Safe (delta)
`ModificatorVentingSpeedDefault`	weapon-wide	Plasma weapon vent variants	Safe
`ModificatorContinousHeatingSpeed`	weapon-wide	Heat-management variants	Safe
`ModificatorStartSpeedForBullet`	shell + delta	Any variants that modify bullet velocity	Safe (shell-tied)
`ModificatorDamageCoefficientSpline`	shell	Damage falloff variants (Heavy Meltagun `_03`/`_04`)	Safe (shell-tied)

Why Only Fire Rate

I do not have a clean answer for this, however the most likely cause is runtime-side: the rate-of-fire value possibly drives a per-shot timer in the shooting system, initialized once at weapon spawn from barrel.shootSettings.fireRate.shotsPerMin. The ModificatorFireRate apply path appears to be a single-shot mutation at spawn time, not re-evaluated when the weapon visual is rebuilt by a skin change. Other modificators (clip ammo, damage, charge duration, etc.) appear to be re-applied during the rebuild.

Whatever the root cause, the symptom is consistent: only ModificatorFireRate has been found to get stripped.

Affected Variants

All seven variants use ModificatorFireRate deltas. The base rate of each weapon comes from barrelDescriptions.common.shootSettings.fireRate.shotsPerMin in the weapon's base description.

Weapon	Tier	Variant	Internal ID	Modificator	Loss on skin swap
Bolt Sniper Rifle	Artificer	Drogos Reclamation - Beta	`brifle_bolt_sniper_rifle_03_b`	barrel `common` -> `fireRate = 80`	80 -> 60 RPM
Bolt Sniper Rifle	Relic	Ophelian Liberation - Beta	`brifle_bolt_sniper_rifle_04_b`	barrel `common` -> `fireRate = 100`	100 -> 60 RPM
Stalker Bolt Rifle	Relic	Ophelian Liberation - Beta	`brifle_stalker_bolt_rifle_04_b`	barrel `common` + `scope` -> `fireRate = 220`	220 -> 150 RPM
Melta Rifle	Relic	Ophelian Liberation - Beta	`shotgun_meltagun_04_b`	barrel `auto` -> `fireRate = 60`	60 -> base auto RPM
Multi-Melta	Master Crafted	Master-Crafted - Gamma	`hwpn_support_heavy_meltagun_02_b`	barrel `blind` -> 50, barrel `aim` -> 90	50/90 -> base/base
Multi-Melta	Artificer	Drogos Reclamation - Beta	`hwpn_support_heavy_meltagun_03_b`	barrel `blind` -> 55, barrel `aim` -> 100	55/100 -> base/base
Multi-Melta	Relic	Ophelian Liberation - Beta	`hwpn_support_heavy_meltagun_04_b`	barrel `blind` -> 60, barrel `aim` -> 110	60/110 -> base/base

Why Heroic Weapons Are Immune

Heroic-tier weapons use a fundamentally different stat mechanism: ModificatorUsingGodlikeModificatorPreset, which references a descriptionOverride block in the godlikeModificatorPresets section of firearm_modificators_library.sso. The override is a complete replacement of the weapon's barrelDescriptions, shellDescriptions, etc. - including barrel.shootSettings.fireRate.shotsPerMin as a baked-in value, not a delta on top.

When the player applies any skin to the Heroic Sniper, the weapon rebuild reads the barrel description as shotsPerMin = 45 (the override is the source of truth, not a delta on top of base 60). The Heroic's lower rate of fire holds through any cosmetic change.

Additionally, applying the Heroic Sniper's skin to the Ophelian Beta variant does NOT bring the Heroic's 45 RPM with it. The skin slot carries only the visual mesh, not the variant's modificatorsGroupName and certainly not the godlike preset. Ophelian Beta variant + Heroic Sniper skin resolves to: variant 04_b's ModificatorFireRate = 100 (stripped on skin swap) + base barrel shotsPerMin = 60 = 60 RPM.

Player Implications

If you are using one of the 7 affected variants DO NOT customize the skin. Keep the variant's default appearance equipped. Any cosmetic swap (chapter DLC, Hordemode reward, color reskin, or even just another variant's look) reverts the rate of fire to the base weapon's shotsPerMin, which negates the entire reason to use the Fire Rate variant. For the 7 affected variants, there is no in-game workaround except "keep the default skin."

Game Files

{CLIENT}/ssl/weapons/versions/firearm_versions_library.sso
{CLIENT}/ssl/weapons/creator/customization/firearm_modificators_library.sso
{CLIENT}/ssl/weapons/creator/customization/firearm_skins_library.sso
{CLIENT}/ssl/main/user/progression/weapons_mastery/appearance/weapon_appearance_library_pve.sso
{CLIENT}/ssl/weapons/versions/modificators/firearm_description_modificator_fire_rate.sso
{CLIENT}/ssl/weapons/versions/modificators/firearm_description_modificator_using_godlike_preset_modificator.sso