Here is my 4th post on alternative mechanics that could be used in a 40k rules re write.

2 staments of fact.
Weapons are designed to inflict damage on a target.
Armour is designed to reduce the amount of damage taken by the target.

Rather than having the weapons damage value ( strenght of hit) reduce the effectivnes of the armour.Which requires a seperate modifier to be subracted from the armour value.(ASM.)(Over complex IMO.)

Give a value at which the armour may save, and over which it has no chance of saving.
(Too simplified and polorises results IMO.)(AP)

Why not just deduct the armour value directly from the damage value?
If we give ALL units a AR (armour -resistance to damage ) value.

This is similar to current vehicles AV values,and for non-vehicles amalgimates all saves and toughness value.

We then get AR values of 1 to 15 to cover ALL units in a standard game of 40k.

If we define weapon effects as A for Area effect.(Anti infantry.)
Each weapon is given a 'target zone', 3" or 6"dia blast,or a template for flame and chemical weapons. {small arms, are fired as a single group}.(All SMG/LMG/HMG/AC/ become bast weapons,)

And P for point contact, ONLY effects one model.(Mainly Anti tank.)

EG an IG squad fire a heavy bolter 6A at a Ork mob AR 2.
Orks in the targeted zone need to roll higher than the A value minus the AR(6-2=4,).
They need to roll a 5+ to save .

If the same heavy bolter was to fire at some SM scouts AR 4.
The Sm scouts only need to roll a (6-4=2)3+ to save.

Obviuosly some targets become invunerable to some weapon effects.
So support (special-heavy) weapons are needed to take on these 'harder' targets.

I would like to introduce the idea of supression into the new game.

IF a unit takes more damage in a turn than its current hit points(HP) + AR value.
(Current wounds + Armour value.)Then it has to take a moral check to see if it is becomes 'supressed'.This is called a supression check.

Eg 5 Chaos terminators ,AR 7. Supression value is 5 +7 = 12.

30 Orks AR 2 , supression value 32.

A IG heavy weapons team with 3 heavy bolters , 6A each.
They cause 3 lots of save in thier target zone , for direct damage.(Orks need to roll a 5+ save or loose models as casualties.)
But also force a supression check in targeted units if thier current Hit points +AR is less than 18.

So the IG fire at the large mob of orks and cause 6 casualties ,(24+2 =26).The orks have far too many left in the mob for the IG heavy bolters to cause them to be supressed.

When the IG HW team fire at the Chaos Terminators, AR 7, they can not cause physical damage to the unit.The Chaos terminators are INVUNERABLE to weapons that cuse less than 8 damage. (6-7 =-1)
However the heavy bolter fire is enough to cause a supression check in the Chaos Terminators.

For vehicles , any hit that is equal to ,or one less than, the rear armour value of the vehicle, causes a supression check.

This is just an example to show how the system could work.
Actual value may be different after playtesting....

What do you think to the basic concept?