I've been looking to speed up combat a little bit and I wanted to try removing the need to roll dice after you've hit an enemy. Rather than just averaging out the d10s and d5s for damage and calling it a day, what I've ended up with is something a little more akin to the Star Wars rules where damage can vary a little more depending on how many successes you score on your attack roll. In addition, this should help remove those situations where you roll poorly on damage and you don't even scratch an enemy through their damage reduction.

The basic idea is all attacks that deal 1d10+modifier damage are now treated as dealing 5+modifier damage. For instance, a laspistol will deal 7 damage rather than 1d10+2. Attacks that deal 1d5+modifier now deal 3+modifier as damage. However, attacks will cause additional damage depending on the degrees of success that you scored on your initial attack. The standard is that you deal 1 extra damage per DoS per damage dice that exists in the original profile. As an example, a single shot with a laspistol that scores 4 DoS will add 4 damage due to the good Ballistic Skill test and it will deal 11 total damage. A weapon that uses multiple d10s, such as a meltagun (2d10+10), and scores 4 DoS will add 4 damage per d10, or 8 damage total in the case of the meltagun. This extra damage is akin to successes granting extra damage in the Star Wars system and it rewards good attack rolls to balance out the nerf to the standard damage potential that arises when averaging the damage dice. I kinda took the idea of swapping out DoS for damage and modified it a bit. I've generated a few of the static melee and ranged weapon profiles from Dark Heresy 2E in the link below to demonstrate how static damage can compare to the current options.

https://drive.google.com/file/d/0BxPSUhvGbW9hNzBCM1AyTXVkd0U/view?usp=sharing

Removing rolling for damage will change a few of the mechanics of combat, especially stuff like Accurate and Righteous Fury. Here are my ideas on how to address each bugbear.

Accurate:

Each additional d10 that would be granted by Accurate now grants +5 damage. However, the extra d10s that are unlocked by Accurate do not grant extra damage for DoS. Accurate weapons only gain +1 damage per DoS per damage die listed on their original damage profile. This should help to make Accurate weapons powerful but not too good at dealing a lot of damage, especially with many DoS you are likely to score with an Accurate weapon.

Primitive:

The Primitive value for a weapon will be halved, rounding up. Therefore a Primitive (7) quality will now be treated as Primitive (4). What Primitive will now do is act as a cap on the maximum bonus damage that an attack can gain from DoS. So a Primitive (4) weapon can, at most, gain +4 damage even if the attack got more DoS.

Proven:

On the flip side to Primitive, Proven will act as a minimum guarantee of bonus damage. For example, a Proven (3) weapon will be treated as having scored 3 DoS on an attack for the purposes of extra damage only, thus granting a weapon a minimum of +3 damage to its profile. These minimum DoS from Proven are not to be considered for things like Full-Auto, Accurate, or Swift Attack and they do not stack if the attack generates more DoS than the Proven value.

Maximal:

Pretty simple. Maximal normally adds 1d10 damage and it will now add +5 damage.

Tearing:

Tearing will allow a character to roll their damage and use the rolled damage if it is higher than the static damage. Tearing attacks still add the DoS on the initial attack roll to the final damage generated regardless of it was rolled or static damage.

Psychic Powers:

The DH2 psychic power system does encourage fettering due to the bonuses to the focus power test. While more DoS on the focus power test will grant extra damage to any attack psychic powers, I believe that there are usually significant trade-offs inherent by fettering such as reduced range, penetration, or other stuff that the change to static damage profiles shouldn't discourage pushing too much.

Righteous Fury and Critical Hits/Effects:

As there are no dice to be rolled, Righteous Fury cannot be triggered in the normal sense. I'm proposing that when an attack is successful, the attacker rolls 1d10. If the result of the die is less than the attacker's relevant characteristic bonus that was used on the attack (usually WS, BS, or WP), the attacker will trigger Righteous Fury. Rather than rolling 1d5 again to determine the effect, the Critical Effect is determined by the difference in the die result and the characteristic bonus. For example, a successful melee attack made by a scum with a Weapons Skill bonus of 3 can only trigger Righteous Fury on a 1 or 2 on the 1d10 and can, at maximum, cause a Critical Effect of 2. In the event that the original attack was not sufficient to deal damage to the target, successfully triggering Righteous Fury will cause 1 damage to the target that ignores the target's damage reduction from armour and Toughness. I admit that this change will cause Righteous Fury and Critical Effects to happen with greater frequency, however it might result in combats actually being decided by people being knocked out due to Fatigue.

Vengeance:

Connected with the changed Righteous Fury rules, Vengeance will grant a relative bonus to the character's attacking characteristic bonus for the purpose of triggering Righteous Fury. For example, Vengeance (9) will grant +1 to the attacking characteristic bonus, Vengeance (8) will grant +2, etc. This will only affect the characteristic bonus when triggering Righteous Fury and determining the magnitude of a critical effect.

Multiple Hits eg. Semi-Auto, Lightning Attack:

The new rules impact on multiple attacks in a few ways. While it does remove the chain critting that can occur as Righteous Fury only triggers once per attack, it compensates by buffing the damage of each individual hit based on the degrees of success. I'm inclined to allow a choice for the attacking character to choose to use individual degrees of success to increase the amount of bonus damage on each shot or "spend" one DoS to score an additional chance at triggering Righteous Fury. This reduction in DoS would only affect the bonus damage that is generated and would not affect the number of hits generated.

I haven't tested these house rules in play so I don't know how effective they'd be in speeding up combat or simplifying damage calculation. I realise I'm effectively trading time spent rolling damage to time spent rolling and checking the critical effect but I feel that could potentially make combat more interesting and exciting. I'm curious to hear what everyone's take on this is.

This is certainly an interesting concept, and I like most of what I see here. My concerns:

-Starting at "average" damage values and then adding more by multiplying DoS and dice together will notably increase damage dealt in combat, particularly because the original DoS mechanic only replaced one die with the DoS rather than all of them. Perhaps you should lower the "average" damage per "die" to rebalance around expected values, considering that if someone hits they're getting at least one if not several DoS.*

-Your issues with Proven interacting with multi-hit attacks will probably be alleviated if you use the above.

-The mechanism for Righteous Fury is a bit wonky considering that you're trying to reduce the number of dice rolled, but then again I'm not certain what to suggest as a replacement. One naive choice would be to trigger it on doubles (a la Eclipse Phase), but then Vengeful doesn't do anything.

-The revised version of Tearing needs a revamp considering that the whole point of this hack is to reduce the complications of rolling and checking a lot of dice. Perhaps doing something like adding +1 damage, +1 per die could work? ( Here's an AnyDice link to the math involved.)

*Just so we're clear, you're familiar with the standard thing that DoS do with damage dice? By default, for any given hit you check the DoS and can replace a single die with that if it's lower than the DoS.

Actually, come to think, how would Spray weapons jam under this system? Normally this happens if you roll a 9 on any damage die, but without rolling you'd need some alternate rules mechanism.

I personally rule at my table that you make the Spray attack roll, just in case degrees of success come into play. Thus, they jam like normal weapons unless things go wrong.

I think you're right NFK and I didn't fully realise how much more damage would be achieved more consistently by taking a flat average. Perhaps it would be more appropriate to have the base damage be 3 per 1d10 and 2 for 1d5. Getting only 1 DoS automatically bumps the damage up as well so it should still be pretty easy to reach the higher amounts of damage compared to the standard rolling.

With Tearing, yeah I wasn't really sure how to work it. I think scrapping the roll entirely and just adding +2 damage to weapons with Tearing would probably be best. That does sync up with the generally higher damage shown in those graphs.

I had forgotten about Spray attacks so I'd be inclined to use MijRai's roll to attack. However there would be no actual chance of failing to make sure Spray attacks don't get screwed over and it would merely be to see if it jams on a roll of 96-00. This would also help to calculate any bonus damage from DoS from the attack roll.

Righteous Fury probably would work better with triggering on doubles as it still matches with the general % chance of rolling a 10 on damage dice. I'm not quite sure how to generate multiple critical hits for one attack that generates multiple hits so I'm considering to allow a single Righteous Fury to be applied to any one particular hit of the attacker's choice.

The Vengeful quality could be applied as a modification on the die roll for the purposes of triggering Righteous Fury. For example, Vengeful (9) would be something akin to Vengeful (1). What this could mean is that Righteous Fury will now trigger on any attack rolls that roll either doubles or one within doubles ie. situations like 23, 67, and 10. The problem with this though is that Vengeful will be very powerful as it increases an 8% chance to a 24% chance with Vengeful (1).