Destiny damage behaviours

I'm actually making a damage simulator for destiny, and it's actually coming out to be pretty precise (it has a range of +-5% damage accuracy).

I've gathered many informations from the whole destiny community, from google and so on, but I'm actually trying to understand some things that are actually quite unclear to me.

First of all, I've pretty well understood that there are several damage multipliers and that, generically, those damage multipliers are actually static.

I've already checked this topic: How is damage calculated?

But I currently didn't find some more informations I need.

From what I've read in the web, sniper rifles, since october 14th have a 2.5 damage multiplier, therefore a sniper rifle with 132 attack and 33% impact should be dealing 326.7 for headshots to mobs of the same level as the player (and It actually works, tested it).

What is bothering me, though, is WHY sometimes headshots on weaker enemies deals about 1000-2000-3000 damage. Is there any bonus for being higher than an enemy target?

A clear example of what I mean is this:

If you consider this video ->

Since the ice breaker at its maximum stats should be having an impact of 28 and a damage of 300, how on earth is it dealing 2851? the sniper rifle precise damage multiplier is 2.5, so how is it dealing that much damage? I'm not really finding any explanation to such a thing, moreover, the rest of my simulations seems to be very accurate, but sniper rifles seems to be reacting very differently regardless their impact and other statistics.

Has anyone a clearer idea of how it actually works?

Thanks,

Briosheje