In another words:
https://www.ibuzzle.com/articles/how-does-a-bullet-work.html
Or in short version: "The ability of a bullet to penetrate and damage its target depends on its size as well as its velocity. Although the bullets are small, they make up for their mass by high velocity, resulting in a higher momentum that is great enough to pierce the target. All this happens in a split second, which is why when seen through our eyes, the bullet seems to reach the target as soon as we hear the gunshot!"
I am sorry, maybe I am too picky, but strength have no influence at damage at all, its have small influence on ability to aim barrel at weak parts of target during fire and handle weight of weapon, but even then - in game it's affect not much since PoE don't have realistic sytem of damage for body parts (or at least something close to Fallout or Wasteland system with precise shots in part of body).
Anyway you right in one point - we need to wait for results of tests (if there would be any ofc) on influence strength on damage with firearms, because without it we can't precise say
how everything fucked how it would be in game.