What do you think about armor rating as HP? So a guy with a plate armour has more hp than someone with a chainmail

What do you think about armor rating as HP? So a guy with a plate armour has more hp than someone with a chainmail.

I think armor should be damage reduction rather than some treshhold you need to overcome. Using it as damage reduction would really give you that "practically invulnerable to most regular weapons" feeling. Imagine in for example D&D having full plate give you damage reduction 10/- or 10/bludgeoning. The only weapons that would be able to harm you (barring bludgeoning, if you choose to make that the exception) would be greatswords and greataxes, and even then they'd only do 1 or 2 damage if any at all. This would also encourage alternate ways to take knights down (like... oh, I don't know... grappling them?).

It'd make the system even more autistic than it already is, but if I could redesign how defending against damage would work I'd do it as follows:
>Replace the term "Armor Class" with something like "Defense Class" or "Protection Class" (sadly both DC and PC as abbreviations are already taken)
>You roll to attack against the targets Defense Class
>Defense Class is basically his ability to avoid or deflect strikes. Dictated by stats and class skills, but can be enhanced by shields and feats
>If you pass this check (ie. you get past the characters defenses) you now have to roll for damage against the armor's damage reduction. As is usual, you roll damage, substract the damage reduction and what remains is substracted from the enemy's hp

This would also allow you to play some animu weeaboo faggot who doesn't wear armor but has an incredibly high defense class because muh speed trumps muh strenght.

>This picture has both plate and mail.

Used that for a time in WoW roleplaying.
nothing=1HP
cloth=2HP
leather=3HP
mail=4HP
plate=5HP
Was serviceable because it is quick and simple.
I feel like it excels in a situation like this where it is more of an auxiliary mechanic. Another thing would be a quick ruling for another scale you don't want to be burdened with too much. Like vehicles. For a main character bound mechanic in a P&P I prefer something more detailed.

In the old 3.5 unearthed arcana, they had an alternate rule giving DR for armor. When playing D&D, I usually describe rolls of less than 10 as a miss, and rolls up to the AC value as a glance or blunted impact unless the weapon has some kind of magic effect or something that would do heavy damage on just a glance.

>wear plate
>take massive damage
>drops to 1 hp
>whew lad it's hot in here, I'll take off my helmet
>dies

This is how the 40k rpgs work, basically. Damage reduction is equal to armor points on the location hit + toughness bonus (CON bonus, basically), and all characters have one reaction per turn they can use tp attempt to dodge/parry and avoid damage, or dp something special. Weapons have armor pen that lets it ignore a certain amount of AP.

Armor reduces damage by a fixed amount. That amount is decreased by any positive difference between armor value and damage received at once.

>Not having extra-hp from armor be the first thing to drop with base hp being what remains.

Independent HP or combined HP?