When my previous group and I got a hold of the Dark Heresy rulebook (practically the day it came out), we were all pretty satisfied with the rules, with the exception of one. We noticed that the rules state you are not allowed to repeat the same half action twice in one round.

A round was described as being a 5 second time period. This, in effect, meant a revolver or shotgun could fire one shot in five seconds. Not only that, after firing that shot, you had a half action leftover which could not be used to just pull the trigger again, often forcing a character into doing... nothing. Having just moved over from the Mechwarrior RPG, this seemed odd (in the Mechwarrior RPG, it was quite easy to empty a 30-round magazine on a target in one round).

So we just decided to say screw it and modified the rule to say that non-movement half actions could be repeated. Then we noticed that semi-auto fire was a Full Action. I don't know about you, but my 'stub automatic' fires a bit faster if I ask it to, so we switched semi-auto fire to a half-action as well, allowing for a single player turn to have action sequences such as two single shots, two melee attacks, and two semi-auto bursts.

It seemed to have the following effects.

  • PCs and NPCs became more able to hit and kill targets during their turn with firearms and melee attacks
  • PCs and NPCs burn through ammo faster, making ammo-conservation a larger issue and reloading in combat happens more often
  • Basic firearms (lasguns, lascarbines, laspistols, etc...) become far more effective, as even a weak enemy with a lasgun or lastpistol was capable of firing six lasgun shots in a single round
  • Everybody goes down quicker and easier, as the volume of fire going back and forth is much higher
  • Full auto weapons seemed to stay at their current power level, but they were still effective

In other words, it seemed to change the balance of play quite a bit. Firearms capable of semi-auto became very useful. Firearms capable of only single shots also became powerful, as now you were able to dump two rounds downrange in a round. To make up for this, more enemies had to be thrown at the PCs, but this increased the volume of fire by a lot, which made it possible for a gunfight to go downhill very quickly with a few bad rounds. It also seemed to take some of the wind out of the sails of melee characters and enemies, but I'm not actually sure if I think that is good or bad considering how powerful it was before. We usually made up for this by adding more melee enemies. All said and done, the fights became extremely tense sequences where every move counted and consequences (and bad luck) piled up quickly. I did notice that some weapons are extremely powerful with multiple shots in a round, such as plasma and melta weapons.

Are there any other unforseen consequences I'm not seeing here?


After getting some answers here and on the FFG house-rules board, and in thinking about what has been pointed out, I think I am going to change the way we've been doing things. I'm planning on introducing two new attack options - Semi-Auto Burst, and Full-Auto Burst.

Semi-Auto Burst behaves exactly as semi-auto fire, but does not gain the 10% bonus on the attack roll. In addition, Semi-Auto Burst is a Half-Action. In the hands of a trained operator, this is a very efficient means of firing.

Full-Auto Burst behaves exactly as full-auto fire, but does not gain the 20% bonus on the attack roll and only gets a single hit per 2 MoS instead of a hit per 1 MoS. In addition, Full-Auto Burst is a Half-Action. It's good for wasting ammo for most people, but can be deadly in the hands of a trained operator.

The following half-actions may be used twice in a single round: Ranged Attack, Semi-Auto Burst, and Full-Auto Burst.

I believe by instead of expanding all half-actions to be 'repeatable' and just naming these three half-actions, it will have the desired effect on the way combat plays out without a lot of the nasty side effects that have been pointed out. Also, limiting these to exactly twice in one round prevents characters who somehow gain an extra action (if I recall correctly, some psyker powers can do this) from repeating it a third time, firing weapons faster than they mechanically are capable of.

The reason I introduced a full-auto half action is because some weapons have a full-auto rate of fire that is less than twice the semi-auto rate of fire. Also, I like the idea of people wasting ammo with pray and spray to little effect. :)

Thanks for the input guys. Will try out the new rules and see how it goes. I don't think it will cause too many drastic changes, as I have sat and watched a guy in carapace armor take 15 lasgun hits in a single round and lose 4 points of health. Having said that, it is very possible that the Full-Auto Burst option will not be hanging around for long when scummers with Autoguns decimate the party. :)


3 Answers 3


You've made two key changes:

  1. Allowing multiple combat half-actions per round
  2. allowing movement to be replaced by a non-movement half-action

The primary factors I see are:

  • increase in Psyker offensive capability (Most of their offense is more powerful than their allowed weapons; it gets worse under RT or DW, due to a different psychic system)
  • decreased access to defenses¹
  • decreased emphasis on movement²
  • increased emphasis on non-action defense (IE, cover)³
  • breaks the equipment bonuses
  • decreases incentives to use burst and full-auto autofire modes
  • cybernetics and talents with extra half-actions become devalued⁴
  • initiative becomes more important⁵
  • Ganging up becomes less essential⁶

¹: Since one gets very few defenses per turn, this change of yours makes them less valuable, by allowing them to be overwhelmed faster.

²: The current system makes movement a valuable and essentially irreplaceable part of the round; take it or not, it's lost if unused or unusable. It's not terribly realistic, but is very cinematic. And DH, RT, and DW are all intended to be very cinematic in tone.

³: At present, especially for melee, active defenses (dodge and parry) are quite valuable; cover is less so, but not enough to render it useless. When one allows replaceing movement with a second attack, cover suddenly becomes MUCH more attractive, as it's an assured penalty to be hit, instead of a roll by the defender... but it also reduces drama.

⁴: At present, the only way to get a second attack is expensive talents and/or cyberware with inexpensive talents. If a character can just hole up in cover and double shoot, these talents are far less valuable, making the Assassin and Guardsman's additional combat actions less useful.

⁵: Further, by allowing the etra attacks, you can run a target out of actions sooner, as well, so initiative becomes more important to prevent having actions drained in defenses.

⁶: Ganging up is the great equalizer in RT and DH combats; it's how one overwhelms defenses. Given that every character can defend once for free, and once by aborting, if you can attack twice, you've just eaten both defenses this round, meaning you only need one attack from a buddy to get through. The norm is that you need two buddies to negate the defenses, or one buddy with a multiple attack talent.

It sounds like you made these changes with rank 1-2 characters... it's going to be more profoundly off-norm or higher rank characters, as normal slow growth of actions is made to feel even slower by providing far less of a bonus over not having them.

  • \$\begingroup\$ Of particular interest is your last statement regarding Rank. While we have tested these rules up to rank 4, I have yet to see the effect at higher rank than that. Will probably need to get in some more playtime and testing before I can reach a definitive conclusion as to the full nature of the effects. \$\endgroup\$
    – James
    Apr 11, 2011 at 18:40
  • \$\begingroup\$ @james One thing else to remember: RT Rank 1 is DH rank 7... and DW rank 1 is DH rank 13... it's more evident in the other games, as the disparity between characters at start is somewhat greater. The changes you've made are not ones I'd consider for my own game; I prefer a much more cinematic, less hiding in cover, feel. \$\endgroup\$
    – aramis
    Apr 12, 2011 at 0:56
  • \$\begingroup\$ To me, space marines, commanders, and storm troopers get the cinematic action, as they can take the heat. I play a guard army in 40k, and cover is life. Different strokes, I suppose. \$\endgroup\$
    – James
    Apr 12, 2011 at 14:52
  • \$\begingroup\$ You can abort your action into a non-reaction dodge or parry? I didn't know that? \$\endgroup\$ Jun 10, 2016 at 2:58

This looks like a pretty major rules change as house rules go. I'm surprised that you didn't turn up more problems than you did.

I think other areas of concern might include whether you allow psykers to activate multiple powers in a turn, how dodges are handled and the effect on equipment bonuses.

  • Psykers can be pretty brutal even at relatively low power levels, doubling their capacity to activate powers might be quite unbalancing.

  • When most characters only have a single dodge, doubling the number of attacks people get could devalue defense significantly. It becomes less a matter of tactics and more a matter of who can quickly bring to bear the most firepower.

  • Also remember that some equipment, such as a laser sight, only works in some modes. It definitely shouldn't be possible o fire two single shots, both with laser sight bonuses, rather than fire a burst without the bonus and only get a number of bullets to hit if you have more than one degree of sucess (it effectively lowers you BS for shots after the first).

All of these could leading to a power escalation in combat that make it difficult for non combat centred characters to contribute.

If you want arguments against this house rule, then I would suggest that you could consider that firstly, you are not supposed to get hung up on the 5 second time period thing. Sure you could pull the trigger multiple times, but could you perform the minimal aiming required for an effective single shot multiple times in a round and could you reload that non semi-auto gun quicky enough to fire a second time in the round?

In most games I've seen, people are far too busy running around, getting into a better position or running to rescue a teammate from the brunt of the attack, to have spare half actions and when they do, an extra 10% chance from an aim seems like a reasonable use of the characters attention.

  • \$\begingroup\$ All good points. You are right in that psykers were pretty brutal - but they already were, as they were effectively the only class that could do two ranged attacks in a round (single shot, psyker half-action). Nullifying some of the defensive options didn't seem to bother us. And instead of negating tactics and rewarding firepower, it seemed to reward firepower and really reward tactics - cover shooting and tactical movement became the default behavior by the players really quickly. Guess we need to play some more and see what else crops up. \$\endgroup\$
    – James
    Apr 11, 2011 at 15:35
  • \$\begingroup\$ @James - The errata clarified that psyker powers are a combat action, so you were not intended to use most powers in a turn where you shoot/melee. \$\endgroup\$ Apr 11, 2011 at 20:55
  • \$\begingroup\$ @MadMAxJr - Hmm, had forgotten about that. Either way, we did not seem to have an issue with our psykers, but that could be because we limited it to a single power per round unless otherwise specified, or because they were too afraid of perils to manifest that often. :) \$\endgroup\$
    – James
    Apr 11, 2011 at 21:01

Are you considering the interactions with move actions? Rogue Trader allows you to move with certain classes of semi-auto fire weapons during the semi-auto action, but you lose the bonus to hit. (Dark Heresy does not have this option.) Since you are reclassifying the action into a half action, a player could simply move then fire, gaining the bonus as normal.

I'm not sure how your players are burning through more ammo, you are still spending the same amount of ammo in a round with or without this change, unless mobility is a factor.

  • \$\begingroup\$ Ah. I may have been forgetting something. I think we also enabled players to repeat (non-movement) half actions, enabling quite a few attacks to happen in a round - two single shots, two semi-auto bursts, two melee attacks... Come to think of it, our rounds were pretty brutal. This may change the question a bit. \$\endgroup\$
    – James
    Apr 5, 2011 at 17:08
  • \$\begingroup\$ I think allowing repeat actions is more of a dramatic impact on rules changes than this one. \$\endgroup\$ Apr 5, 2011 at 17:20
  • \$\begingroup\$ I agree. I had forgotten about that rule change because we made that rule change on day one and never looked back. It does change things quite a bit. I liked the effect, personally, as did the group. The semi-auto as half-action was what we were iffy on, as it made already deadly ranged combat even deadlier. \$\endgroup\$
    – James
    Apr 5, 2011 at 17:23

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