Following my DH game today I had a brief discussion with one of my players about the importance of Toughness, armour, weapon damage, weapon penetration, the problems and/or inconsistencies that arise in these mechanics, and some of the issues with vehicle armour/structural integrity. After this discussion, I sat outside having a smoke, and came up with the following ideas:

Note-These House Rules (intended for use with from-the-book Dark Heresy, meaning no DH/Black Crusade-hybrid rules) do not change the mechanics of Righteous Fury.

Called Shot- This Attack Action becomes a Free Action, imposing a -20 penalty to BS, and can be used in conjunction with the Standard Attack, and the Half Action and Full Action Aims. Used in conjunction with the Half Action or Full Action Aims, the Called Shot penalty to BS may be mitigated or negated, otherwise the Called Shot is more difficult, and the PC is simply hoping to hit his mark at the expense of using less time…time she/she may not have in dire circumstances. The following House Rules for Accurate weapons are therefor intended to work with this new Called Shot mechanic.
POV- Called shots are typically used to hit soft or unprotected targets, but I see their purpose being greater than that obvious potential, such as: you want to stop a fleeing suspect without killing him, so you casually unholster your Scalptaker and shoot him in the leg (specifically) hoping for a crippling critical ("Yeah, I'll getcha a bandage, just as soon as you spill it!"); you want to punch through the turret plating of a Chimera command variant in hopes of taking out the platoon Lieutenant, so you leap into the liberated Autocannon nest and swing the barrel around…; you want to nick a fly from your best mate's pate on a dare; etc. Called shots are the stuff of legend, like Babe Ruth pointing to the wall. Achieving your goal won't necessarily be an easy thing, but you should at least be free to make the choice to look like a total badass on a whim, hence I've made Called Shot a Free Action, yet it still has an associated penalty.

The Accurate Quality- This game mechanic does not change, insofar as receiving an additional +10 to BS in addition to the bonuses for Half and Full Action Aims.

Accuracy- Pistols: Extra damage may be inflicted, dependent on the wielder using a Half Action (calculates up to 1 DoS) or Full Action (calculates up to 2 DoS) Aim. Example- The wielder of an Acurate Pistol uses a Half Action Aim, shoots his target and achieves 3 DoS; calculating up to 1 DoS (for the Half Action Aim), the wielder will do additional Damage equal to the Penetration value of the weapon x1 (Penx1). Using a Full Action, the wielder may count up to 2 DoS, so the extra damage inflicted would be Penx2. Pen values of 0-1 are counted as 2 for purposes of calculating extra damage inflicted.

This would give Accurate Pistol weapons (such as the Needle Pistol) with low base damage and/or low/nil Pen the additional punch to make them worth consideration of use. A Full Action Aim with a Needle Pistol that achieves 2 or more DoS would do d10+4 R Damage, Pen 0 (Toxic), allowing a greater chance of punching through the collective armour/Toughness protection of a target in order to introduce it's Toxic Quality. It would also make the Khayer-Addin Dueling Las (Pistol; the "Valentine") perform to the expectations of its description; with a Full Aim Action and 2 or more DoS the "Valentine" would do d10+12 E, Pen 4 (Tearing). The balance of this rule is reflected in individual weapons' Clip sizes, Reload times, Availability, Cost(s), prerequisite Talents and their costs, and other already-existent factors inherent in the rules. As noted above, the mechanics for Righteous Fury remain unchanged in light of this House Rule.

Accuracy-Basic: As for Pistols, except a Half Action Aim Allows for the addition of up to 2x calculated Pen-damage per DoS, up to 2, and a Full Action Aim up to 4x calculated Pen-damage per DoS, up to 4. By way of example, a PC with a BS of 49 takes a Called Shot Free Action (-20) and takes a Full Action Aim (+20) with a standard-issue Long-Las (Accurate; +10), and rolls an 08 to hit, achieving 5 DoS. The resulting Damage would be d10+3 (base) +8 (4 [max possible] DoS x calculated Pen-damage 2), Pen 1. The same PC, using an Angelis Boltgun, taking the same Actions and achieving the same DoS, would do 2d10+20, Pen 5 (note the Angelis does not have the Tearing Quality), further justifying its illegal/proscribed nature. Again, Basic weapons with a Pen of 0-1 treat their Pen as 2 for calculating additional Pen-damage inflicted.

Pen-altering/increasing Ammo Types- Use the altered/increased Pen value to calculate Pen-damage as normal.

Using the above House Rules to address weapon Pen values in conjunction with vehicle armour- Without delving too deeply into the math, just glancing at it over its surface, I think the above rule could be applied to every weapon (not just those with the Accurate Quality) when the target is a vehicle. Obviously, there are going to be to-hit Size modifiers that increase the chances for greater DoS, but if you apply a slightly different formula to the calculations it will still leave some weapons woefully incapable of affecting armour (vehicles), barring the occurrence of Righteous Fury…or Zealous Hatred, as the case may be. Not many pistols should be expected to throw the track of a Leman Russ MBT. The adjustment would look something like this:

Any Accurate Pistol or Basic weapon works exactly as described above. So, obviously, a standard-issue, run-of-the-mill Laspistol has little (if any) chance of punching the glacis plate of a Leman Russ MBT without successive RF/ZH dice. Basic and Heavy weapons that do not actually possess the Accurate Quality are treated as having the Accurate Quality when targeting a vehicle, though they do not receive the additional +10 BS bonus for aiming. Basic weapons use the Pistol Pen-damage calculation rules (see above), and Heavy weapons using the rules for Basic weapons (see above). No more needing to be within half listed range for Melta weapons to double their Pen value (I think that "quick fix" is crap). The "Valentine" would max out (barring RF/ZH) at 26 points of Damage (including its Pen), which is 12 points short of punching the front armour of a Chaos Dreadnoght (see 'Rites of Battle). A Mk III "Sunfury" Plasma Pistol would max out (barring RF/ZH) at 38 (including its Pen)…just enough to ding that Dread. An Astartes Meltagun (Deathwatch; pg. 145)…67 points, including its Pen, which is more than enough to blow a hole into a Land Raider. An Astartes Missile Launcher (Krak; Deathwatch; pg. 150)…64 points. It's worth mentioning, these are MAXIMUM damage quotes, assuming 10s rolled on all dice, not accounting for RF/ZH…and a Land Raider starts with a Structural Integrity of 95. You'd be lucky to take a Land Raider with less than ten (standard) Melta blasts. A Tech-Marine with the right Talents could squeak out a few more points, but that's otherwise as it should be.

IMPORTANT NOTE! In all instances, PCs MUST use the Called Shot Free Action in conjunction with an Aim Action (Half or Full) in order to benefit from the additional Pen-damage calculated. NPCs with the Touched By Fate Talent may use these House Rules.

I approached these House Rules from the viewpoint of Accurate Basic weapons being meant for use at range, not up close and personal. I'm tired of the close-range (8-17m) firefights including "sniping" weapons. I know it's an issue of meta-gaming and min-max gaming…blah, blah, blah. Telescopic Sights will remove extreme-range BS penalties, Silencers will reduce the chances of a target reflexively ducking (and thus fouling a shot) due to the sound of a weapon's report. Or, the silent Needle Pistol can be used at close range (say from just around a corner) to temporarily knock out the Enforcer left overnight to watch over the scene of a recent murder, and with less-than-lethal injury. Or, the "Valentine" truly becomes the one-shot dueling las-pistol of the rich and "cultured" upper hive spires. I'm trying to encourage ROLE playing.

These rules may add a little more time due to calculations. But honestly, if your players don't know the Pen values of their weapons and how to quickly calculate DoS by now, what does a little more time matter? The Core Rule combat mechanics are cumbersome in any case. And besides, I don't like adding dice to damage pools, as doing so seems (to me) to be counter-intuitive. Hence adding damage based on DoS.

These rules could be transported over to Deathwatch and/or Black Crusade, but here are some suggestions:

Felling-The Felling Quality continues to work as described.

Razor Sharp- The Razor Sharp Quality is treated as the Accurate Quality, but for melee weapons. (I have recently imported the Razor Sharp Quality to my Dark Heresy game; in this case, all damage-type R melee weapons with a Pen value [natural or upgraded] are considered to also have said Quality, using the multipliers outlined for Pistols [see above]. It has worked well so far, and served as the foundation for the House Rules in this post.)

The Emperor Protects,
Commissar Alekzanter Kurn, XLVII Horan Jezaliers

I don't understand the problems that these rules are supposed to fix. Also, as I understand it, you can already use the Aim action with the Called Shot action, so your house rule is confusing.

Also, people can dodge a bullet just by hearing the noise from a shot? I had the impression than it was impossible for a human, even a super human, to dodge a bullet that has already been fired.

One example of a problem fixed: Needle Pistols become an option. Otherwise, they're Damage d10 vs. Flak (AP 4) and Toughness 4? Not really an option. Sure, they're Accurate, but I want the weapon to do a bit more damage (4), not a significantly increased amount of Damage (potentially 20). I want the Needle Pistol to remain a stealthy weapon, not suddenly become a body-blowing, blood-spraying Noisy Cricket.

If you prefer, ignore everything referencing Called Shot. It's primarily included due to the combat sequencing of other 40K RPG Core Rules.

And you can Dodge ranged attacks. That's how the system works. Someone shoots at you, they hit, you get a chance to Dodge, if you fail they roll Damage.

Ah. I think that is where you are going wrong. Damage is not literal. I could reasonably narrate a 500 damage hit as something that is silent and unnoticable because the rules are abstractions. They are not a simulation of reality. A needle pistol that hits for 30 damage will be just as loud or visible as one that does 5 damage. Nothing changes.

I meant something different with the dodge question.I have personally interpreted dodging a bullet as this. A character doesn't literally dodge a moving bullet, that would be as impossible as catching said bullet in your teeth. What the character does is move out of the the specific line the bullet would take before the shot is even fired. There is no reason to say this in the rules because it doesn't have any bearing on the game mechanics. It is only relevant to the narrative of the game.

@Alekzanter: Can you clearify? I really don't understand any of what you posted. I believe that a "Called Shot" is just that a called shot that takes no time at all to do, so in essence it's already a free action in a sense.

With the Accuracy rules described are you replacing the extra damage that accuracy rule gives you of the extra d10 per 2 DoS up to +2d10 with 4 DoS? Because it seems that you are limiting the possible damage out put on low Pen accurate weapons and only making some hig Pen accurate weapons damage out put as average and also lowering possible RF by having to roll only 1d10 and not 2d10 on 2 DoS or 3d10 on 4 dos. And if you apply it to all range weapons then your adding extra damage to all weapons and making range combat very deadly if anyone uses manstopper rounds seeing this would add +3/+6 damage for pistols' Half/Full action aims and +6/+12 damage for basics' Half/Full action aims.

And is there a minimum distance that you have to be away from your target to use these rules, to prevent you from having a fire fighting 8m-17m away from each other?

How do you dodge range attacks if you don't get a reaction to the range attack if they are hidden away snipping at you?