Well sort of, it becomes more a matter of ammo effieciency and if you run into the regenerator enemies one needs to have either good weapon skill, alpha damage or be able to hit it quicker than it regens.

In the labs you can run into things like 3 varieties of hulks at the same time, so kelvar( fire damage really good against them), normal and one I cannot recall the name , but births raptors

There is also the military tiers zombies ( they are fairly well protected against bullets) and some of them are quite nasty if you are unfamiliar with what they can do.

5.56mm is a good base line weapon to judge how dangerous something is, can handle the less armoured enemies pretty well and should be able to harm armoured with FMJ rounds although for the heavily armoured ones it is either high caliber, bash or explosives to do the damage quick enough.

9mm can work decently well against the less armoured enemies, but it might not do enough without having autopsy proficiency to get the weakpoint crits in. It might struggle a bit with the soldier zombies and will bounce off the kelvar tier ones though.

Big advantage of guns is how quickly it can stack bleeding, so an SMG with skill would probably work well with a hit and run approach to wear down an enemy.

I personally try to favour melee and use guns as a "panic" button of sorts if I need to kill high priority targets. Having something anti-armour helps a lot and melee is the "cheapest" option in regards to maintainence and reliability.

Noise makers can be pretty useful, I have seen a funny sight in the game world where an active speaker spewing loud messages, I could read the combat log before I saw it, with blade traps and the zombies just walked to their doom as the blades cut them up from the I assume momentum of trying to get to the sound.

I learnt the building demolition trick from narrowingly having a building miss my character when an electric zombie blew out the walls of an apartment when it interacted with the propane tanks.

But to the point, a molotov in a building makes a lot of noise when the building collapses and zombies path to the noise source and die to the fire.

There is a definitive answer, but I try to guess that the sound value seen on guns is like a radius, the lower calibers are usually quieter than the higher calibers of course. The 5.56 when fired feels like about a full zoomed out square and a bit radius as I taken a military base by sniping with a m4a1 and would draw agro from about that far out.

I guess from the idea of if I could hear it in real life, then I mentally model that in best guess idea of if I use something then I should expect a certain amount and the zombies will converge of the source of the sound it hear - so if use a grenade in a city I haven't cleared then I expect a lot of movement towards the point of explosion and get far away before I could get overwhelmed.

In a lab situation, I have had "oh shit" moments where the zombies are fairly closely packed and shooting a gun leads to a swarm. Found the best way to handle it is the fall back to a choke point and molotov or 2 the choke point, and fight off the wave and try and kill them before they make it through the fire.

In regards to weapon carry, I prefer the point sling on the front, I have had moments where the gun gets damaged with the shoulder sling modification and it does increase the gun profile- I suppose it is part of the payoff of being a universal attachment. Also the encumberance- from last I played- is better when it is connected onto the single point sling. It is more a means for maintainence and encumberance cutting to reduce penalities where I can.

There is also the more tactical stuff like the rigs and harnesses and they are good as it distributes the weight better and provide a lot of useful pockets however it is a bit of a balancing act with both the layering and the durability of it, as it feels like clothing on top of your armour.

Which is why I settle on the sling, gets hit a lot less.

If you are going for a more ranged character though, I would probably recommended the survivor distributed rigging with a survivor harness. Minor encumberance penalties if you align it right but you get a good setup for holding a weapon with a couple of clips and olds and ends in the pockets.

Could also go for a Molle setup, and slap on the type of pouches you want and use something like a harness or an appropriate loadbearing vest with sling, doesn't feel as good and heavier and less versatile compared to the survivor setup but the parts should be easier to make or pick in loot.

If the gun is too big, there is also the double rifle bag one can use for the higher profile or a heavily modded 2-handed gun.

Another option is to use a type of military backpack, and clip the gun onto the bag, things I dislike about the bag is the chance the weapon flies off and the encumberance getting too high if I cannot manage the looting. Could always drop the bag of course, however I prefer having things secured and in arms reach at all times when I engage in combat.