It seems that this is not the thread for you.
You think that guns in D&D suck, and that's fine. This thread is for someone who would like to work out how to use guns in D&D.
Best to move on to one of the thousands of other interesting threads, please.
Thanks
On the contrary. I am against the reason that guns should be disallowed or restricted because they might change the balance of the game and be a danger to a potential wizard cast, as Jürgen Herbert theorized, simply by the fact that they don't do much damage, compared to the other offensive capabilities that trained magical monsters, or summoned beasts, or your average magician can do. In terms of game balance, a gun is nothing special, compared to magic missiles and fireball, even worthless. Non-magical bows and crossbows aren't restricted in normal settings, because they don't do that much damage, and fireweapons, who at best do 2d8 damage (and those are stats taken from D20 Modern, with modern fireweapons, so actually, the damage of a blunderbluss or whatever older firearm there is should be even less), won't by that reason ever pose a danger to spellcasters either.
In a semi-realistic way for your average fantasy setting like the FR, Eberron and whatnot, guns would never appear, because there are better alternatives that make more damage and are more reliable than even our modern firearms.
But if you want guns in your game, then you don't need to worry, because they couldn't possibly ever be harmful to a setting in terms of damage, nor ever alter the course of history.
That's why guns suck, compared to the more powerful items already prevalent in every standart D&D-game. There would be no change at all on the battlefields of D&D, no socio-political effects due to peasantry rising against their overlords, or the invention of battle-cannons, because desintegrating rays, magic missiles and cloudkill are all more efficient than whatever gunpowder-weaponry could ever accomplish.
Do I dislike fireweapons in a fantasy game? Surely not. I played Wizardry and Final Fantasy, games where people in medieval-style armour and swords run around and fight dudes and dudettes with guns and laserweapons. When I say they suck, then I mean they are so weak, nobody would make a fuss about them. Spellcasters who can summon forcefields to shield themselves from arrows won't fear bullets either.