I tested on Moze so I can’t be sure how special modifiers factor in for other classes, for instance I know Amara’s Driver com factors in but I haven’t tested to be sure where it fits in. I haven’t tested annointments so I’m not sure on what’s best there but the general formula is:
Chuck dmg = Normal hit x Splash x Grenade x bullets in mag x Elemental Modifier
Normal hit encompasses all the additive boosts a character gets times the card damage. So in Moze’s case this is pretty much everything, you can see Moze damage formula for specifics. Com boosts to Weapon Damage and Manufacturer damage also fit in here. Important to note however com boosts to smg dmg, pistol dmg etc are not part of normal hit and do not effect the reload damage.
Splash is all boosts to splash and area of effect, these boosts are additive to each other.
Bullets in mag is quite self explanatory, the only special case is an empty mag has the same damage as 1 in the mag.
Elemental Damage is again self explanatory. For the case of multiple elemental buffs they tend to be additive to each other. So for Moze with 3 stoke the embers and an elemental projector verse a fire enemy in tvhm the calculation is:
Fire mult x Elemental buffs = 1.75 x ( 1 + 0.3 + 0.9 )
Tediore chucks count as grenades and splash so on Moze they receive bonus fire damage from Fire in the Skag Den. The Fire in the Skag Den damage however is based on normal hit damage and will scale with more bullets in the mag. But gains no bonus from splash or grenade bonuses.
The chucks however don’t receive bonus fire damage from Selfless Vengeance, I didn’t test Cloud of Lead or Experimental Munitions so can’t be sure for them. The after exiting IB gain 40% bonus fire damage for 2 mags has no effect on reloads
Pull the Holy Pin will also allow tediore chucks to crit.