As much as I love this game, it has few irritating issues. One od them is a quantity of different loot types.

 

I am currently un like 2/3 of a game and I have tons of rings, capes, armors and melee weapons. Each of my 6 team member has two rings, unique cape/armor, unique weapon and I have reserves of few unique rings, capes, armors and melee weapons. Meanwhile I have mey with like three boot/helmet/gloves/waist/unique ranged items so far. Uhm... Did I do something wrong?

 

Also it seemed for me there is a third firearm weapon type after pistols and muskets in a game, according to wiki there are "blunderbuses" or something like that. Oh well I have yet to see one - even generic

Yea, during my playthrough I didn't find many belts, helms and boots either during Act 1 and 2. Assuming you don't buy any from vendors, not every party member is going to be equipped with one. Didn't really bother me though, I'm fine with some slots being harder to find. The first really strong (pun not intended ) belt I got was

Belt of Maegfolc Might off a Leaden Key assassin at Stormwall Gorge at the start of Act 3

As for helms, I picked up a few Stag Helms later on.

One from an adventuring party at the Dragon Egg. Another from somewhere in Twin Elms.

Regarding blunderbusses, I'm also generally fine with firearms being rare, considering the general level of technology in Eora and Dyrwood, during that period. I believe I didn't pick up any at all until really late into Act 2. Might have been a random one from a crate.

Got a Fine Blunderbuss off a Skaenite cultist just before the Blood Pool (assuming you're approaching from the bridge). The really notable one would be Leadspitter which you get off Rumbald for finishing his quest (pretty strong opening strike weapon for Eder against any foe with low-moderate DR).