Absolutely, it's the core design feature of escalating HP that makes guns mechanically incompatible with D&D. [...] Unless they are ridiculously unbalanced (a problem in and of itself), PCs won't react to them in any way we would recognize as sensible.
When it comes to
realistic combat, the problem with hit points is
not that a high-level D&D fighter
can survive a dozen sword cuts, spear thrusts, or gun shots, but that he
cannot die by any one attack.
Also, for whatever reason, people want guns to be realistic, in a game system where no form of combat is.
I actually don't disagree with that notion that no weapon is handled realistically in D&D, but I feel that some kinds of combat are handled better than others.
For instance, in a sword-fight between two knights in head-to-toe armor, it does not strain credibility that they exchange multiple blows before one of them lands the telling blow, and that even the winner is rather beat up by the end. That seems realistic, and it matches the fiction; go back and read Le Morte D'Arthur for countless examples. Is it a perfect model of knightly combat? No, but it works, because we expect most sword blows against armor to be less than final, and because we expect the fighters to be worn down over the course of the exchange.
For other kinds of fight, the system does not match expectations nearly as well. In a samurai movie, we expect a fight to be settled by one decisive hit. Hit points can handle this well, I suppose, as long as no one has enough hit points to survive a single katana-stroke. In such a hyper-lethal system, no one would survive a second hit.
Western gun-fights tend to follow the same pattern as samurai-movie sword-fights, where a quick-draw is vital, because the weapons are hyper-lethal. Plot-protection rarely comes in the form of withstanding many hits, but rather in not getting hit: spotting the ambush just in time, shooting the attacker just before he shoots, etc.
A more realistic gun-fight would involve less-lethal guns, but not less-lethal in the D&D sense of causing no real harm until the
nth hit. A .22 pistol, for instance, can kill you dead in one shot -- or not.
Before the machine gun, closing to melee range was a reasonable strategy -- and the D&D rules would be a reasonable medium.
Even before the machine-gun, rifled muskets were lethal against massed infantry in the American Civil War, and some experts recognized that the new-fangled "magazine rifles" firing "smokeless powder" rounds would make the next war, the Great War, a war of entrenchments.
But, yes, marching at the enemy was a perfectly reasonable tactic for
centuries. The attacking force would take
some casualties from a volley or two, and the defending force would (hopefully) break and run at the sight of "cold steel" (bayonets).
With D&D-style hit points, anything that
might kill you with a single shot
will kill you with two, so guns have to be extremely lethal for this to play out "realistically".
The challenge isn't the actual lethality of the weapons in question, but the perceived lethality. There's this Hollywood-induced perception that modern projectile weapons are one-shot-one-kill wonder weapons, which while occasionally true isn't generally the case. But people expect firearms to be significantly more lethal on a single-shot basis, and then get disappointed if you don't play them that way.
Again, the problem is that we know guns can kill people -- competent or incompetent -- with one shot, and single-shot guns have been used throughout history for dueling and hunting.
With D&D-style hit points, anything that
can kill you with one shot
will kill you with two -- and vice versa -- so we have to make guns unrealistically lethal to get the "realistic" result that they
sometimes kill people and animals with a single shot.
If wounds didn't involve hit points but were instead save-or-die, a not-so-lethal little .22 could still have a 1-in-20 chance of killing someone (or something) with no guarantee that the second, third, fourth, or
tenth shot would be lethal.
Here's what we learned: the older weapons -- knives, bolts/arrows, musket balls -- generally caused equal or greater damage, given a hit, than modern weapons. The reason for the ultimate widespread adoption of firearms is that you can dramatically increase probability of hit, at longer ranges, with significantly less training, with a modern weapon than you can with prior generations. So muskets replaced bows and crossbows, which were in turn replaced by rifled weapons, which increased in range and rate of fire ...
In fact, a modern assault rifle round is deliberately weak compared to old battle rifle rounds, because the initial concept of an assault rifle was a weapon with the full-auto capabilities of a submachine-gun, but with longer range than a pistol round can deliver. Thus, it uses an "intermediate round" -- between a pistol round and a true rifle round -- that travels further than a stubby pistol round, but without the kick of a full-power rifle round.
And if troops are going to fire at full-auto, we want them to carry as many rounds as possible, so smaller-caliber, lighter rounds make the most sense.
That's not how American troops use their assault rifles these days, but that was the theory for a few decades.
Anyway, looking at this through D&D lenses warps the relative importance of damage. Almost any rifle round designed for combat or for deer-hunting is going to have plenty of potential to kill any human it hits, but very, very few rounds find their target. In fact, very few
troops find their target before firing; they don't ever see who they're shooting at. Instead, they fire
thousands of rounds into the tree-line or into suspicious looking buildings for every
one that hits an enemy. (It's like they think they'll hit on a natural 20, but real life's rules don't work that way.)
And at shorter distances, where both sides might see each other, most troops can't "take their time in a hurry" and manage to use their sights and control their trigger unless they feel really, really safe behind good cover or with no incoming fire.
D&D-style hit points invert the relative importance of hitting at all and hurting someone once you've hit them, leading to odd in-game consequences. For instances, when you're going up against the toughest hombre in town, the obvious answer is... to bring a Buffalo rifle, because it does the most damage, and soaking up damage is what "tough" guys do, right?
