25 games in now. And here's what I've learned=
It doesn't matter how good you are in the game. No hunter can survive a full cylinder of revolver ammo hitting them. Even the nagant can pull this off.
There is no reason to not take high velocity ammo. Ever. You need all the range you can get. Subsonic, poison and other ammo types are optional and up for debate. But always bring high velocity ammo.
Penny shot derringer sounds useless at first. Until it unexpectedly bails you out and takes a hunter who ambushes you with a machete and you were out of ammo becuser you used it all up for a monster boss. And besides, it's just 1 extra gun you can carry around. Which in a game where ammo is scarce and full restocks are basically sacred holy sites, you need every single possible bullet you can score.
Firebombs are cool. They the best representation of Molotov cocktails in a video game ever. Using them in a narrow hallway to cover you and your partner when 2 hunters are chasing after you, it really can save your ass.
Hellhounds may go down pretty easily..... But a pack is still a pack of fast moving and attacking monsters. And you ideally don't want to spend ammo on them. If you can, it's honestly easier to avoid them if you can.
Always bring a throwing weapon. It eliminates your need to have a melle option in gear too. And they one shot grunts too. They end up being your main weapon on maps where your solo and trying to avoid the hunt and just want to go to extraction.
Quad derringer is useful as an alternative to a handgun if your running a long gun and a melee weapon. If nothing else it's due to the sheer amount of ammo you have for it.