Mass Effect 3 Message Board  

If you have the Gibbed Save Editor for Mass Effect 3, know that you can put multiple Weapon mods - and multiple copies of the same weapon mod for an additive effect - for a weapon that either Shepard or a Squad member carries around.
->Open the Gibbed ME3 Save Editor
->Open your save for your character
->Switch to the Raw tab
->Under the Section 3. Squad Player, is your weapon Mods section (you click on the [...] to open up the new window)
->You can either add a weapon and put in the weapon class name section the desired weapon, like SFXGameContent.SFXWeapon_SniperRifle_Javelin
Or
SFXGameContentDLC_EXP_Pack003.SFXWeapon_AssaultRifle_Lancer
->Then open up the [...] next to the weapon mod class names and add something like (if sniper):
SFXGameContentDLC_Shared.SFXWeaponMod_SniperRifleSuperScope
SFXGameContent.SFXWeaponMod_SniperRifleDamage
SFXGameContent.SFXWeaponMod_SniperRifleReloadSpeed
SFXGameContent.SFXWeaponMod_SniperRifleTimeDilation
SFXGameContent.SFXWeaponMod_SniperRifleConstraintDamage
SFXGameContentDLC_EXP_Pack003.SFXWeaponMod_SniperRifleUltraLight
SFXGameContent.SFXWeaponMod_SniperRifleReloadSpeed
SFXGameContent.SFXWeaponMod_SniperRifleConstraintDamage
SFXGameContentDLC_EXP_Pack003.SFXWeaponMod_SniperRifleUltraLight
SFXGameContent.SFXWeaponMod_SniperRifleReloadSpeed
SFXGameContent.SFXWeaponMod_SniperRifleConstraintDamage
SFXGameContentDLC_EXP_Pack003.SFXWeaponMod_SniperRifleUltraLight

For Henchmen The process is pretty much the same.

NOTE: Some weapon mods I found to have an opposite effect, like the SFXGameContent.SFXWeaponMod_ShotgunAccuracy Actually makes the shotgun less accurate if you copy multiple lines of it into the desired weapon.
Also, I have modded with a coalesced editor my weapon mods, so perhaps adding multiple lines of the same weapon mod might not have the same effect as I had, but do try and test this for yourself, say you save outside the spectre requisitions office and edit that save, then when you try it ingame, you have a good place to test out your weapons, the shooting range.
NOTE2: If you even go to the "MODIFY" window ingame on a weapon bench/the squad loadout window when entering a new mission, your weapon mods will be reset from those specified in the save editor, because it doesn't normally allow more than 2 mods on a single gun.
NOTE3: Because of the above limitation, I find that the first moment you find yourself ingame with a squad and infront of a weapon bench, I tend to just add to all weapons for all members some weapon mod (doesn't matter what) only because I feel lazy about copying in the save editor multiple new guns. So that when I open up the save editor, I can see for Shepard and my Henchmen the weapons available and what weapons they have modded, and I can just add into it (I have a text file with all weapon mods copied so I can simply copy-paste the needed names).
You can still perfectly freely switch your weapons, and the mods stick on the weapons for all squad members as long as you don't go into the ingame weapon mod window to switch them around.
So once you've added weapon mods to a gun or multiple guns, you can switch when you feel like it the gun around, and still have the mods in place.

If you want early ingame all weapon mods and weapons for that matter, open up a coalesced bin editor, in the bioinput.ini section, go to sfxgame->sfxgamemodedefault->bindings to add a key binding for either executing a text file into which you can add the weapons+mods as you please, or add into the keybinding itself all the weapons&mods you want. Example:
( Name="F11", Command="giveitem self SFXWeaponMod_AssaultRifleMelee | giveitem self SFXWeaponMod_AssaultRifleSuperScope | giveitem self SFXWeaponMod_AssaultRifleUltraLight | giveitem self SFXWeaponMod_AssaultRifleForce | giveitem self SFXWeaponMod_AssaultRifleMagSize | giveitem self SFXWeaponMod_AssaultRifleStability | giveitem self SFXWeaponMod_AssaultRifleDamage | giveitem self SFXWeaponMod_AssaultRifleAccuracy | giveitem self SFXWeaponMod_SniperRifleSuperScope | giveitem self SFXWeaponMod_SniperRifleDamage | giveitem self SFXWeaponMod_SniperRifleReloadSpeed | giveitem self SFXWeaponMod_SniperRifleTimeDilation | giveitem self SFXWeaponMod_SniperRifleConstraintDamage | giveitem self SFXWeaponMod_SniperRifleUltraLight | giveitem self SFXWeaponMod_SMGPenetration | giveitem self SFXWeaponMod_SMGStabilization | giveitem self SFXWeaponMod_SMGAccuracy | giveitem self SFXWeaponMod_SMGMagSize | giveitem self SFXWeaponMod_SMGStability | giveitem self SFXWeaponMod_SMGConstraintDamage | giveitem self SFXWeaponMod_SMGDamage | giveitem self SFXWeaponMod_PistolAccuracy | giveitem self SFXWeaponMod_PistolDamage | giveitem self SFXWeaponMod_PistolMagSize | giveitem self SFXWeaponMod_PistolStability | giveitem self SFXWeaponMod_PistolReloadSpeed | giveitem self SFXWeaponMod_PistolUltraLight | giveitem self SFXWeaponMod_PistolSuperDamage | giveitem self SFXWeaponMod_PistolHeadShot | giveitem self SFXWeaponMod_PistolPowerDamage | giveitem self SFXWeaponMod_ShotgunAccuracy | giveitem selfSFXWeaponMod_ShotgunDamage | giveitem self SFXWeaponMod_ShotgunMeleeDamage | giveitem self SFXWeaponMod_ShotgunReloadSpeed | giveitem self SFXWeaponMod_ShotgunStability | giveitem self SFXWeaponMod_ShotgunUltraLight | giveitem self SFXWeaponMod_ShotgunSuperMelee | giveitem self SFXWeaponMod_ShotgunDamageAndPen | giveitem self argus | giveitem self avenger | giveitem self cobra | giveitem self collector | giveitem self falcon | giveitem self gethplasma | giveitem self mattock | giveitem self reckoning | giveitem self revenant | giveitem self saber | giveitem self valkyrie | giveitem self vindicator | giveitem self carnifex | giveitem self eagle | giveitem self ivory | giveitem self phalanx | giveitem self predator | giveitem self scorpion | giveitem self talon | giveitem self thor | giveitem self claymore | giveitem self crusader | giveitem self disciple | giveitem self eviscerator | giveitem self graal | giveitem self katana | giveitem self raider | giveitem self scimitar | giveitem self striker | giveitem self hornet | giveitem self hurricane | giveitem self locust | giveitem self shuriken | giveitem self tempest | giveitem self blackwidow | giveitem self incisor | giveitem self indra | giveitem self javelin | giveitem self mantis | giveitem self raptor | giveitem self valiant | giveitem self viper | giveitem self widow |giveitem self sfxweapon_assaultrifle_cerb_gun01 | giveitem self sfxweapon_assaultrifle_quarian | giveitem self sfxweapon_shotgun_quarian_gun01 | giveitem self sfxweapon_smg_bloodpack | giveitem self sfxweapon_smg_geth_gun01 | giveitem self sfxweapon_sniperrifle_turian_gun01 | giveitem self sfxweapon_assaultrifle_krogan_gun02 | giveitem self sfxweapon_assaultrifle_lmg_gun02 | giveitem self sfxweapon_pistol_asari_gun02 | giveitem self sfxweapon_pistol_bloodpack | giveitem self sfxweapon_shotgun_assault_gun02 | giveitem self sfxweapon_shotgun_salarian | giveitem self sfxweapon_sniperrifle_batarian_gun02 | giveitem self sfxweapon_shotgun_geth | giveitem self lancer | giveitem self silencer | giveitem self sfxweapon_assaultrifle_prothean | giveitem self sfxweapon_assaultrifle_geth | giveitem self sfxweapon_assaultrifle_lancer | giveitem self sfxweapon_pistol_silencer | SetAllWeaponModLevels 5" )