How do legendary weapon effects work with shotguns?

Question

In doing some weapon research, I've read that others prefer the "Explosive" legendary effect on shotguns and laser weapons with the beam-splitter, since they've reported (such as here) that each separate pellet/beam of the shot will gain that effect. There are a few other weapon effects that seem to affect on a "per shot" basis which leads to a few questions. Namely:

1. Freezing/Incendiary/Irradiated/Plasma-infused/Poisoner's/Two-shot/Wounding: Are all of these effects also on a per-pellet basis?
2. Staggering: Does each pellet have a chance to stagger?
3. Instigating: If an enemy with full health is hit with, say, 4 pellets, will all 4 of them get the 2x damage bonus for Instigating? I suppose the answer to this could be dependent on whether or not all pellets of a shot "hit" at the same time.

Answer 1

Per Shot: Irradiated, Freezing, Plasma Infused, Incendiary, Poisoner's, Furious.
Per Projectile: Wounding, Explosive.
Untested: Status effect only legendaries (Kneecapper, Stagger, etc.) and damage multipliers (Powerful, Exterminator, Two Shot, etc.)

Damage-Over-Time doesn't stack. (Except for Wounding.) So even if they are per projectile, they are effectively per shot.

I just tested this myself with a couple sets of console duplicated semi-automatic laser rifles (maxed Rifleman perk, game version 1.7). Focused vs Splitter for each legendary tested. Used a brahmin as target practice (no VATS), and measured damage. There was no difference in damage with the per-shot legendary effects. By comparison, the split per-projectile legendary effects did vastly more damage than their focused counterparts.

Answer 2

1)Freezing/Incendiary/Irradiated/Plasma-infused/Poisoner's/Wounding: I know for sure all these get the effect for every pellet. All you have to do is look at the damage they do when all the pellets hit a single enemy or the fact you can deliver the effect on 2 enemies close together with a single shot if the pellets hit both. I'm not sure about the two-shot effect though don't see a reason why it wouldn't but haven't seen a shotgun with that effect yet.

2)Staggering: I'm not 100% sure about the staggering effect but I would say yes just based on the fact you can perm stagger enemies with a combat shotgun with this effect even legendary enemies.

3)Bloodied/Instigating: Bloodied is based on the players health the bonus is better the lower your health is and each pellet gets the bonus fine. I haven't seen an Instigating shotgun yet so I can't comment on how the effect would act it would be 100% speculation.