There’s another variable at play here: how many points do you have in your weapon skill? Enemies die a lot faster when your critical chance is at 75% rather than 25%. Especially with that 50% critical damage boost when you get the skill to 40, and the 20% aimed shot damage boost at 60.
The game is easy enough that you don’t really need to put skill points into ranged weapons, but it dramatically boosts your damage output.
My first playthrough I spread my points out pretty wide, assuming the game gave you too many like most modern RPGs. I did have 100 in long guns at the end though and the inmates in the final "dungeon" were still super bullet-spongey. I was mostly using the sniper rifle from distance with bullet-time headshots and shotgun up close. I had all the crit chance boosters. It really depended on the enemy though, a lot of them would die from one headshot but Mantiqueens? Fuck no, bullet-spongey as hell.
Note a lot of this might depend on subjective thoughts as to what "bullet-spongey" is. I prefer less hits both ways, i.e. enemies die more realistically in one headshot or a couple body shots, but I die quickly too. If pumping a whole clip into a Mantiqueen isn't bullet-spongey to you, then there's our problem.
Normal mode is a joke because you one-shot almost everything and they barely damage you at all.