I feel like we're talking past each other, because the samurai duel is an example I made earlier, in another thread, of a similar situation where D&D's hit points don't match either reality or, more importantly, genre expectations. And, of course, the 3E version of Oriental Adventurers tried to work around this with its iaijutsu bonus damage, like sneak attack bonus damage, on a first strike off the draw.
So, again, the problem is not specific to guns; it's just worse for guns than for many other weapons. When you have a lethal one-shot weapon, like a dueling pistol or a Kentucky long rifle, and it can't kill another duelist or a deer (or a British officer), it's more jarring than if a kitchen knife can't kill someone on the first slash.
I'm pretty sure a huge monstrous spider could and would kill a first-level halfling rogue on its first successful bite. In fact, with a +9 attack bonus, it would likely hit, too.
(In fact, if we want to open a whole 'nuther bottle of worms, the problem with playing Bilbo in D&D is that he's not high-level, but he has a lot of plot-protection, which is normally implemented in D&D via high hit points.)
Again, I think we've been talking past each other, because I have repeatedly made the point that early matchlock guns weren't much different from crossbows, and they could use the same stats, since armies of the time saw them as roughly equivalent.
D&D doesn't handle guns or crossbows "well" -- if you care about dueling, hunting, stopping a charge, etc. -- so the more important such missile weapons become, the weirder the game plays.
What is it about blackpowder weapons that you think I'm misunderstanding?
Really? You keep saying that blackpowder weapons need different rules.
They don't.
It is not 'worse for guns' - at least when you give them a decent damage and a good multiplier. In short, when you pretty much give them the same damage and crit multiplier as an axe. You get chopped with an axe, you can die. You get shot with a big soft ball, you can die.
A d10 or a d12 with a X3 multiplier is quite scary enough for blackpowder weapons - like your huge spider bite, it will put Bilbo in the ground with one lucky hit - from straight up damage from the large die, or the multiplier if you are really lucky. (For what it is worth, I picture the Mirkwood spiders as Large, not huge - but Tolkien was not trying to be a taxonomist of outsized arachnids.)
Chop Bilbo with a greataxe, you now have a half-halfling.
Shoot Bilbo with a musketoon and you have a halfling with a hole in the middle - each is equally dead.
In short - you are making things more complicated then they need to be.
If you want anything like realism from early guns - most shots
didn't kill. People even survived shots to the neck. (Gustavus II Adolph coming to mind.)
Most shots that did kill were fatal days, weeks, or months after the battle - it was not unknown for a festering lung wound to kill years after it was inflicted.
And this was true for swords, bayonets, and axes - not just guns.
The grim truth is that most deaths were horribly delayed - infection, peritonitis, and loss of lung capacity.
You want realistic
anything? Play something else.
I just assume that a weapon is a weapon - a tool designed for killing people.
In the real world axes were more lethal and easier to use than swords - swords needed training. An axe is likely a lot closer in lethality to a gun up into the 17th century than any sword.
The warhammer developed to penetrate armor.
The basic poky stick (i.e. spear, pike, lance) was the basic weapon for most of history - including the early twentieth century in the person of the bayonet. Good for standing off an enemy, at least until they get within its reach.
None of these need special rules, except for the long spears. The game does not really need or support such complication.
Clear enough now? If you are going to 'fix' one thing then fix all, don't concentrate on a single weapon, thinking that it is likely the only one shot, one kill weapon.
D&D also does not have proper rules for duels, be it with claymores, pistols, or katana. Oriental Adventures did try to address this, turning the samurai into a professional duelist.
It is also worth mentioning that the only known duel between a westerner and a samurai did not go as some might think - the samurai cut the Portuguese nearly in half, but it didn't much matter, since the samurai had been run through at the same time.... Neither had any defense for the other's attack, with tragic results. Again, dead is dead.
The Auld Grump