create mod folder like this

your mod name
--mod info.lua
--units
--projectiles

place "UEB2305" unit bp and script into units folder
place "TIFMissileNuke01" projectile bp and script into projectiles folder

modify unit UEB2305 like this = ProjectileId = "/mods/yourmodname/projectiles/TIFMissileNuke01/TIFMissileNuke01_proj.bp",
modify projectile as you wish.

100% works

you may have to adjust mesh if you dont include those files aswell

It looks like I'm doing something wrong, but here's what I got.

There's a mod "Merge," which makes changes to units. It works. I'm using it.

ProjectileBlueprint{
Merge = true,
BlueprintId = "/projectiles/TIFMissileNuke01/TIFMissileNuke01_proj.bp",
Economy = {
BuildCostEnergy = 5,
BuildCostMass = 5,
BuildTime = 6000,
},
}
im use your values, and 100000 too.
As a result, the nuclear silo doesn't build missiles. It doesn't consume resources and there's no loading bar. There's no shell inside either. I changed the energy mass and build time values—the result is the same. When i press the missile launch button and select a point, the silo opens, the siren sounds, but the missile doesn't launch. That is, there's no missile in it, and it's not being built.
What am I doing wrong?

ProjectileBlueprint{
    Merge = true,
    BlueprintId = "/projectiles/TIFMissileNuke01/TIFMissileNuke01_proj.bp",
    Economy = {
        BuildCostEnergy = 9999,
        BuildCostMass = 9999,
        BuildTime = 9999,
    },
}

Haven't tested it but it should work.

In Supreme Commander: Forged Alliance, Nuclear Missiles are Projectiles, not Units. Therefore, you cannot change their build cost or time in a standard UnitBlueprint file (like your main mod file). You must edit the Projectile Blueprint located inside the game's archive files.
Step 1: Locate the File
The file containing all projectile data is named projectiles.scd.
Default Location: C:\Program Files (x86)\Gas Powered Games\Supreme Commander Forged Alliance\gamedata\projectiles.scd
️ Note: .scd files are archives. You cannot open them with Notepad directly. You need an unpacking tool.
️ Step 2: Unpack the Archive
You need a tool called GPGPack (often included in FAF modding tools or available separately).
Download and extract GPGPack.
Drag and drop the original gamedata\projectiles.scd file onto GPGPack.exe.
It will create a folder named projectiles containing many .bp files.
Step 3: Find and Edit the Nuke Files
Inside the extracted projectiles folder, look for files related to nuclear missiles. The IDs usually follow this pattern:
UEF: NU0401.bp (or similar)
Cybran: NC0401.bp
Aeon: NA0401.bp
Seraphim: NS0401.bp
Open the relevant file (e.g., NU0401.bp) in a text editor like Notepad++.
Look for the Economy section inside the ProjectileBlueprint. It might look like this:
lua
12345678910
Edit the values:
Increase BuildCostEnergy (e.g., to 60000 or 100000).
Increase BuildCostMass (e.g., to 6000 or 10000).
Increase BuildTime (e.g., to 1200 or 3000). Note: 60 ticks = 1 second.
If the Economy section is missing in the projectile file, the cost might be defined in the Silo Unit blueprint instead. However, in most cases, editing the projectile file works for strategic missiles.
Step 4: Repack the Archive
Once you have edited the files, select the projectiles folder (the one containing the .bp files).
Drag and drop this folder onto GPGPack.exe.
It will generate a new projectiles.scd file.
Step 5: Install into Your Mod
To make the game use your modified version:
Take the new projectiles.scd you just created.
Place it inside your mod folder structure:
YourModName/gamedata/projectiles.scd
Launch the game with your mod enabled. The game will load your projectiles.scd instead of the original one, applying your new costs and build times.
Summary Checklist
Download GPGPack.
Unpack gamedata\projectiles.scd from the game directory.
Edit NU0401.bp, NC0401.bp, NA0401.bp, NS0401.bp (change BuildCost and BuildTime).
Repack the projectiles folder into a new projectiles.scd.
Put the new .scd file in YourMod/gamedata/.
This is the most reliable way to balance Nuclear Missiles without breaking your existing unit modifications.

This is right?