This is probably going to make me look a bit stupid, but where exactly in the rulebook does it say that shooting breaks concealment. I just can't find it.

Also, are there any rules on how far someone can see in different light conditions? All I can find are modifiers on ballistic skill tests, but nothing that tells me if I'm simply out of sight for someone.

Rhel said:

I don't know that it's written out clearly, tbh, and as far as I read it doesn't say directly that shooting breaks concealment.

What it does say is in order to conceal yourself it's a half action. Awareness checks are free actions. If you wish to oppose the free action everyone gets to find you after you've shot at them, you must be making half action concealment checks. So it's not that cover is broken so much as targets get awareness to detect you.

This is further implied from the section on stalker rounds being used in a stalker rifle that reads: Additionally in such a weapon, no Tests to detect the shot are possible (however, depending on the situation, the appropriate Opposed Skill Test may be required for the firer himself to remain hidden).

So when you read those two things, it seems to imply in most situations firing a gun is loud and noisy and would require the shooter to make active concealment checks against his opponents. With the right weapons his opponents might not know where to even begin looking.

As for darkness and light conditions, I use the BS test chart. Darkness I consider to be at night. If it's pitch black and completely lightless, and Marines aren't equipped with their gear, I would treat it as a failed awareness test and say the character can't act against the target he cannot see. If they know something is there, give them X% chance to hit with a spray and pray or the like. I do not think there are specific rules on it.

Ok, that really helps with the concealment. Thanks.

Although, how does that work against a group? Do I just make one check against the highest awareness in the group? If not it seems like I can only hide from two people at once.

On the sight range thing. Does that mean that by the rules characters can see infinitely far? I'm asking because I intend to play as a sniper kind of character in game I'll be in and the way I understand the rules, even if I'm standing 2000m away from the enemies, as soon as one of them turns around if I'm not concealed he'll see me.

Which, tbh seems a bit weird.

If multiple characters are sneaking they should all roll their concealment against awareness (since one guy might be better at sneaking etc.). Although it is reasonable to believe a single character would roll one awareness test and compare it to all the concealment tests. One of the sneaking guys may have made a mistake and become visible, but the observer may not see the other 9 guys with him.

FFG doesn't have any hard and fast guidlines set for sight ranges. This is a continuing issue I have with the game, since each GM has to 'decide' for himself how this works without any guidelines set beforehand.

There is some reference a human with good eyesight (20:20) can detect human shaped objects out to 2 miles, but at that range the human eye is no longer able to distinguish two tiny people from each other if they are standing close to each other (1-2m).

Out to 1 mile a human should be able to identify a being (and in 40k reference its species) relatively simply, though getting details such as equipment or style of clothing and gender would not be possible.

The point where a human is capable of seeing and recognizing another being or specific object without concious thought or action (awareness tests) is a much shorter distance. I would say this would be within 50-100 meters depending on persons and training. A soldier or pilot is going to have better perception than your average civilian.

Then you have situational effects such as darkness, haze, or particulate air (sandstorms etc.) that will all play an effect on vision. We all know its harder to see in these situations, but getting good details for them is a little harder than visual ranges.

Just to put a number on them I'd say in twilight (half-light or dawn/dusk) visual detection ranges are half. Vision in moonlight would be 1/10 the range, and 1/20 the range for starlight. Obviously total darkness is nothing.

Hazy situations should decrease detection ranges by 1/3 to 1/4 depending on severity.

Particulate air (sand/snow storms) should decrease detection down to mere meters: from just a few to 10 or 20 depending on severity.

To put it into game terms lets say the following:
AVG Human sight range:
Range to notice 2m (average size) object: 3km (awareness tests for movement +/-10 for every 200m)
Range to identify 2m (average size) object: 1km (w/awareness test +/-10 for every 100m up to +/-50)
Range to identify 1m (scrawny size) object: 500m (w/awareness test +/-10 for every 50m up to +/-50)
Range to auto-notice 2m (average size) object in the open: 75m
Dawn, Dusk, Twilight: 1/2
Moonlight: 1/10
Starlight: 1/20
Haze: 1/2 - 1/4 (-10 to 30 to awareness tests)
sand/snowstorm: 3-20m (-20 to 40 to awareness tests)

Space Marines have much better sight (heightened senses) so we can easily assume they can see farther and better.
Space Marine sight range:
Range to notice 2m (average size) object: 5-6km (awareness tests to determine movement +/-10 for every 400m)
Range to identify 2m (average size) object: 2km (w/awareness test +/-10 for every 200m up to +/-50)
Range to identify 1m (scrawny size) object: 1km (w/awareness test +/-10 for every 100m up to +/-50)
Range to auto-notice 2m (average size) object in the open: 100m
Dawn, Dusk, Twilight: 3/4 100% with auto-senses in helmet
Moonlight: 1/2 100% with auto-senses in helmet
Starlight: 1/4 100% with auto-senses in helmet
Haze: 1/2 - 1/4 (-10 to 30 to awareness tests) Not affected by superior vision
sand/snowstorm: 3-20m (-20 to 40 to awareness tests) Not affected by superior vision

Thats just a quick stab at a few rudimentary guidelines for you and anyone else. This is a great opportunity for the community to hammer out these guidelines for each other, and I for one would love to see a post concerning these. Feel free to use/ignore/improve upon to your hearts content.

Wow… I wasn't expecting anything this detailled. Thanks, this'll help a lot.

Now I've got just one question left, I think.

The rulebook says that when using a silencer, or stalker rounds, the awareness test to hear the gunshot can only be made at half the normal distance.

What IS the normal distance for hearing a gunshot? Are there also no rules on this?

There are no rules on the "normal" distance to hear a gunshot. Basically the GM decides how far away they might be heard, halves it, and if anyone is still in range take note of it.

Though truthfully it is quite a complicated issue anyway… hard and fast rules would be hard to put in place. But generally… quite some distance.