Hi all, I've been working on a classic 40K hybrid ruleset and wanted some honest and constructive feedback.

My Goal: develop a vehicle damage system that I believe keeps the Armour Value/damage-table feel of older editions without the biggest problems of either 4th/5th or the Hull Point system of 6th/7th, while also being as thematic and flavorful like mid-hammer rules are known for. Also, it must be easily portable into any mid-hammer edition, and lastly, is simple and easy to remember.

My Ask: Open and constructive feedback/playtesting about how it works in game (simulations and numbers can only go so far), does it alleviate the issues of older editions even if only partially, and most importantly, is it thematic and fun. After all, maybe the issues I'm referring to weren't as big of a deal as I remember.

My basic overview from research and overall various community feedback over the editions:

• 4th: vehicles are swingy. A normal penetrating hit basically had a 50% chance to destroy the vehicle outright.
• 5th: Mathematically**,** these rules reduced a normal penetration to a 33% chance of destruction and made glances much less lethal. However, vehicles were also known to absorb repeated damage, and, on the extreme end with luck, could basically be immortal. This is where a ton of mechanized/vehicle heavy lists became the meta.
• 6th/7th: The addition of Hull Points attempted to solve that problem, but made every glance effectively a wound. A normal 3 HP tank is guaranteed dead after three glances, even if its armor was never actually penetrated. Vehicles became easier to kill again. Hard capping of health wasn't necessarily an issue, but glancing vehicles to death was.
• This System: make penetrating armor matter, make repeated penetrations progressively serious, but don't let marginal glancing fire simply drain a vehicle's health bar.

Diving right into it. The Rules:

Hull Points are removed from normal vehicles.

The Vehicle Damage Table is slightly changed from 5th:

Modified D6	Result
0 or less	No Effect
1	Crew Shaken
2	Crew Stunned
3	Weapon Destroyed
4	Immobilized
5+	Vehicle Destroyed

The modifiers remain, including Glancing −2, AP− −1, AP1 +1 and Open-Topped +1.

The major addition is:

Cumulative Penetrating Damage: Every time a vehicle survives a Penetrating Hit, it gains a permanent +1 modifier to subsequent Penetrating Hit damage rolls. Glancing Hits neither gain nor increase this modifier.

Basically it alters the math favoring more penetrations trending towards a guaranteed kill. HP values do this, but in a different manner:

• First penetration: 33.3% chance to destroy.
• Second penetration, if it survived: 50%.
• Third: 66.7%.
• Fourth: 83.3%.
• Fifth: 100%.

Cumulatively, ignoring the additional possibility of being killed through Weapon Destroyed/Immobilized, a vehicle is about 33% likely to be dead after one penetration, 67% after two, and so on.

Now, lets pause here to address the elephant in the room, as I'm sure some people are questioning the need for this at this point, or that is basically pseudo Hull Points*,* or, based on your percentages a vehicle has 5 HP now.

In summary - we have a clear, simple progression of damage to a vehicle without leaning on a hard cap of 6th or 7th Hull Points, but also increase the chances of destruction versus 5th edition was purely chance, taking an ungodly amounts of penetrations if you rolled well, or the coin flip rules of 4th.

I can see a pseudo HP argument being had here, which I understand. My goal here was to basically have a similar system but remove the hard cap (3 HP on a Leman Russ for example) while still retaining of aura of: Crap, the more damage I take, the less time I have before tank go big boom.

What we're left with is a system in which vehicles are both tougher than 4th, 6th, and 7th vehicles, but significantly reduced staying power than in 5th.

This is how things math out:

1st penetrating hit we're still in-line with 5th and 6th, but significantly reduced chance of outright destruction from 4th edition. This is fine, fresh combat vehicles that haven't taken damage righty should have a higher chance of survival.

System	First lascannon penetration destroys vehicle
4th	50.0%
5th	33.3%
6th	33.3%
7th	16.7%
Our rules	33.3%

Further math including glances: This is where the custom rule damage curve really starts to show its benefits.

After three successful damaging hits (glances or penetrations), the approximate chance the target has been destroyed increases:

System	Predator AV13	Leman Russ AV14
4th	~77%	~70%
5th	~53%	~42%
6th	100%	100%
7th	100%	100%
New system	~63%	~49%

As noted in the table above, 4th edition is incredibly lethal to vehicle. 5th edition over tuned this, resulting in extremely tough vehicles. GW put a band-aid solution in 6th and 7th using Hull Points as a definitive way to prevent 5th edition vehicle issues being basically immortal. I don't think this a hard cap was necessary and resulted in glancing vehicles to death. Its basically a bigger infantry model at that point.

This custom system puts us right in the middle of 4th and 5th, the former being too swingy and the latter being potentially unrealistically too tanky. There will me more to this later in the post.

This gives repeated penetrations a natural escalation without tracking Hull Points.

Wrecked vs. Explodes!

In summary - more penetrations = guaranteed higher chance of a destroyed vehicle. More penetrations you survive, the higher chance of a critical system or ammo detonating, and causing an explosion.

This is more thematic and probably a bit more realistic than just rolling solely on the damage table.

Vehicle destruction is separated from the main damage table. Here's where we retain some flavor elements of the game.

The accumulated Penetrating Damage modifier also applies to this roll (basically, on a 6+ the vehicle explodes, but add the penetration modifier).

That means a relatively intact tank that is destroyed is unlikely to explode on a first penetration, while a tank that has already suffered multiple penetrations becomes increasingly unstable:

When Vehicle Destroyed is rolled:

D6	Result
1–5	Wrecked
6	Explodes!

Percentages of an explosion based on number of penetrating hits:

• No accumulated modifier: 16.7% Explodes!
• +1: 33.3%
• +2: 50%
• +3: 66.7%
• +4: 83.3%

Running simulations with repeated penetrations all the way to destruction, roughly 65% ultimately become Wrecks and 35% Explode.

So catastrophic explosions exist, but they're associated much more strongly with heavily penetrated vehicles rather than simply getting lucky on the damage roll.

This mechanic was deliberately added, as I stated earlier I felt the more you penetrate the armor, the higher chance there would realistically be of either hitting something important, like ammunition in storage, fuel stored in the vehicle, etc.

Glancing Hits

Summary - 3 glancing hits do not cause vehicle death. that never made sense to me. Basically, my thoughts are: scratching paint on your expensive main battle tank shouldn't just kill it after 3 hits....

Glances still roll on the damage table at −2, so they can Shake, Stun, destroy weapons and Immobilize vehicles.

They just don't accumulate the penetration modifier.

The old cumulative component rules also apply: additional Immobilized results become Weapon Destroyed, and once an immobilized vehicle has no weapons remaining, further Weapon Destroyed/Immobilized results can finally destroy it.

This means glancing fire can eventually kill a vehicle, but it is very inefficient compared with actually penetrating its armor.

In simulations, any tank profiles set against exclusively glancing hits needed roughly a dozen-plus glances, around 15 in the examples tested, to be destroyed through accumulated component damage.

Compare that with a 3 HP vehicle in 6th/7th:

Not fun. Not Thematic. 👎

Full comparison using actual shooting (many tests omitted for brevity)

Simulating a BS4 S9 AP2 lascannon firing into the front armor of a Predator (AV13) and Leman Russ (AV14), including misses, failed penetration rolls, glances, penetrations:

Approximate average lascannon shots required to destroy against front armor using new system:

System	Predator AV13	Leman Russ AV14
4th	~7.6	~13.1
5th	~12.5	~23.4
6th	~7.1	~11.3
7th	~8.0	~12.4
New system	~9.5	~18.6

Notice the difference between vehicle heavy 5th, and weaker 4th editions here. This rule puts us in the middle almost directly.

Here's the detailed table of penetrations and their expected outcomes. The more you penetrate, the higher chance of killing. The more penetrations survived, the higher the chance of an explosion:

Penetration	Vehicle Destroyed chance	Explodes if destroyed	Explosion chance on that hit
1st	33.3%	16.7%	5.6%
2nd	50.0%	33.3%	16.7%
3rd	66.7%	50.0%	33.3%
4th	83.3%	66.7%	55.6%
5th	100%	83.3%	83.3%

Again, it's thematic, less swingy, and not capped to a HP value that can be simply glanced down, while still retaining some mechanic of degradation.

With Hull Points, once successful damaging hits occur (glances or penetrations of an exact specified amount) ultimately accomplish the same thing: a dead tank. This rule is not tied to that.

Here, actually punching through the armor remains important without tying to just hit a hard cap of Hull Points, but still giving you some type of meaningful damage progression.

Percentages of how lethal these rules are based on AV per Edition in percentages:

AV	vs. 4th	vs. 5th	vs. 6th	vs. 7th
AV10	13.4% less lethal	34.1% more lethal	25.6% less lethal	1.1% more lethal
AV11	14.5% less lethal	33.6% more lethal	27.0% less lethal	2.2% less lethal
AV12	16.6% less lethal	33.0% more lethal	29.2% less lethal	7.1% less lethal
AV13	20.5% less lethal	31.0% more lethal	33.7% less lethal	15.4% less lethal
AV14	29.7% less lethal	26.0% more lethal	44.3% less lethal	33.5% less lethal

Once again - pretty much in the middle of everything, where I'd want to be. Stronger that 4th, 6th, 7th, but weaker than 5th.

Melee

I also simulated dedicated melee anti-tank units because the cumulative modifier could theoretically make multiple Power Fist/Klaw penetrations excessive.

I'm omitting these results since melee is basically a guaranteed kill all around.

Because melee anti-tank would basically cause an immediate explosion of a vehicle and cause themselves damage, I decided that penetrations from melee attacks to not carry over to the damage table. Otherwise, they would always be hit by an explosion basically every single time.

Final Points

The easiest way I'd describe the resulting system is:

Numerically, it's more durable than 4th/6th/7th but less durable than 5th (see table), with the additional durability particularly noticeable on heavily armored vehicles because converting a penetration into a glance actually matters.

It keeps the old AV/damage-table uncertainty, removes Hull Point hard cap on health, prevents endless 5th-style penetration survival, and makes dedicated anti-tank weapons meaningfully better than simply throwing huge quantities of marginal Strength fire at vehicles to glance to death.

Overall through all simulations including those omitted, this vehicle system is roughly 25–35% less lethal than 4th, 6th and 7th Edition, while being roughly 25–30% more lethal than 5th Edition.

However....

Maybe I am overthinking everything, and maybe these issues weren't as prevalent as I am thinking. Maybe this whole thing was an exercise in futility and boredom. You will have to tell me. Were these editions as brutal to, or overly helpful to vehicles? If you do play test it be sure to let me know how things compare.

If you all want to give it a shot and let me know your thoughts so I can adjust where needed for my own games that would be extremely helpful.