I have every intention to keep this topic alive.
I genuinely curious if it boggles someone’s mind as mine or it’s just nitpicking on my side. Sadly I discovered some people that actually defend recoil.
@OrsonMaxwell, @Drakonhammer, thanks for your contribution.
Lets just say warhammer laser weapons have recoil simulators to compensate for the 30k~ years of recoil weapons. Without it, the guardsmen would fall into heresy ;D
Ok lasguns dont have recoil, its just a empty tube with nothing inside
Its ridiculous to think that scientists here, WELL VERSED in non existent future energy beam weaponry could be wrong
Guardsman pulls the trigger, then magic happens and poof out goes laser pointer light, gun doesnt even heat up and EVEN if it did, there is a small invisible notebook fan cooling the system that several thousand degrees energy beam creates
Jesus christ could you even begin to imagine that there could be ANY part inside cheap made weapon in the trillions that could even remotely be responsible for recoil
Me neither 
Even I amitted a couple of posts ago that lasers in fact do have recoil but it’s insignificant compared to the recoil of firearms. So there will be no visible animation of said recoil.
I like how you despise facts about science but certain about fictional components of lasgun that exist within your imagination. And you get frustrated that people don’t follow your logic.
Iam amazed
Some people are denser than neutron stars
I already agreed with you!
Fictional energy based weaponry shooting laser that flashboils liquids cannot POSSIBLY have recoil since what comes outside has 0 or almost 0 mass
AND THATS IT!
There will be NO discussion of how ALL that energy is stored, transported, condensed, focused, released, chamber then cooled and preprared for a next release could POSSIBLY create force inside a ficitonal futuristic cheap made energy based weaponry that would be similar to recoil modern day powder weapons make.
Its laser = no recoil
Leaving the science aside, would you prefer lasguns with recoil animation as it is in the gameplay trailer or without?
with
All guns in every game i’ve played in my whole life have recoil and leaving it out now would honestly “feel” weird. Its like the chainsword perfectly cutting through everything one swipe or the ogryns combat knife stopping on every pox walker. To each their own. Im sure a mod could fix it for you
As I mentioned before - what will make lasgun any different from any other automatic rifle aside from visual and sound design?
Another thing that should be also changed is the impact of the laser shot. There should be no kinetic impact: it’ll either burn the target or cut through it without pushing.
Yeah, that’s why they put small computers into vehicles that utilize variator transmissions so those computers can synthesise the fake 'vroom! ’ sound and feed it to the car’s speaker system. True story 
The reason the lasgun has recoil is because of the machine spirits. They didnt get oiled properly, someone used cheap incense, the person giving the incantations had a cold and the machine spirit hated how it sounded. Et voilà, recoil.
I don’t know where your weird obsession with cooling systems → recoil comes from, I am thinking Tzeentch? Or how cheapness/crudeness is going to make a laser weapon recoil without actively designing an unnecessary mechanism for the parts to simulate the recoil of a normal AR. Like are you picturing a liquid cooled gun that vents a mass of liquid forwards with every triggerpress like some giant laser-supersoaker hybrid or what?
You do know many HMGs had water or air cooling systems and it didn’t magically affect the recoil, right? (Well apart from making the weapon heavier meaning it recoils more slowly)
Lasguns happen to have a barrel replacement system so basically the hot barrel is swapped out for a cool one. A manual barrel swap wouldn’t cause recoil at all. You need a mass - projectile, propellant gases - leaving the front of the gun with every round to give recoil with every triggerpress.
All this suddenly makes me realise I’d love it if FS included barrel-swapping, but I assume they’ll probably only have the powerpack heating as a mechanic. It would be kinda neat to throw an overheated powerpack since the IG sometimes use them as improvised grenades in the lore.
It’s ironic when this is the genuine best explanation in favour of lasgun recoil in this entire thread.
Maybe whoever designs lasguns in the 41st millenium drives a Tesla M3? Checkmate, Elon Musk haters!
I would want lasguns to have no recoil.
Or at least have no more recoil than from 9mm pistol. Or some small shake when fired.
But its more or less my preference. I can’t solidly base it upon science or fluff.
Because
it’s the future tech achieving impossible feats by today standards, in such a small package(!).
inner workings of lasgun aren’t explained at all in lore. Its just a battery pack -> lasgun go pew.
What i can speculate, is this:
Noticeable recoil could only come from inner working mechanisms related to discharging or cooling/venting.
Take into account the incredible heat the beam produces (punches holes in people/blows off limbs, with such a short duration). The inner mechanisms and barrel would be so hot, I think the air venting would be completely ineffective for cooling.
With how the lasguns look so compact, i speculate that the overheat problem is solved just by sci-fi materials that simply withstand the heat.
Another possible reason for recoil is discharging and some kicking parts in the case. But in fluff the lasguns are described as simplest and most reliable weapons, better than autoguns (ARs) in those characteristics. You could bash people’s head with it and it would continue working. That gives me an idea that inner workings don’t have moving parts, or at least no parts that will kick the weapon as strong as .308 rifle. (In trailer the lasgun recoil was quite strong).
Sure there could be high speed mechanical contactors that actually ‘go off’ when you fire and also re-coсk themselves somehow for the next shot, but it is still more probably that power switching is done via solid-state devices.
The future tech argument basically contradicts the overheating argument frankly, because any and all tech always was and always be bent on efficiency. So no matter how much energy gets carried by the beam itself, the rifle should dissipate the less portion of it the more ‘advanced’ we’re trying to picture it.
As for venting, I’m yet to hear what exactly should it vent, where this something is stored if the only ammo for the rifle is the battery pack, and most of all, why this something must be vented both at supersonic speeds (in order to have an actual kick comparable to a firearm which spits out a chunk of lead at supersonic speeds) and it absolutely must vent it strictly forward.
lasers might not have recoil but heat needs to be dealt with especially in precision tools/guns.
todays guns face serveral problems due to heat, and many armys value the ability to quickswap barrels in their all purpose machineguns.
now compared to todays weapons i would assume that a lasgun capable of exploding bodyparts off the heat must be unendurable even for the most heat ressistant metals we know, or at least for extended periods
after thinking about how to solve both the heat and the “laser = no recoil” problem i thought about tanks
In autoloading tanks they flush air through the barrel so the propellant gases leave faster and the next shot can be archieved faster
If i were to come up with a reason to why a lasgun of 40k specifics had recoil it would be something alike
(not taken from lore or anything)
after the laser discipates a cooled gas is vented through the barrel, to allow for a barrel to be used for the duration of an engagement. this causes a slight noticable kickback. The kickback caused by this is nessecerary due to the frequency of shots possible)
Being serious and talking pure lore here for a moment: the barrel swap system (like MG42s and some other irl weapons utilise) is in the actual wh40k lore. I seem to recall mention of heat sink rings with Death Corps of Krieg lasguns? But don’t quote me on that.
To the best of my memory I have never seen any explicit mentions of air or liquid cooling when it comes to lasguns, but I’m all ears if someone has a source.
Going back to recoil: the most plausible explanation for lasgun kick I have heard is that the weapons were artificially designed to recoil with every triggerpress so they’d feel more like an autogun (and that the early lasguns were largely training weapons for autoguns), but none of the people giving this explanation actually said what exactly this mechanism is beyond handwaving it.
At the point where lasguns are a mass-produced, common weapon, you’d think most guardsmen would be used to there being no recoil on the standard-issue IG weapon. Not to mention, more importantly than all these other considerations, having no recoil is a massive advantage, you’re actively gimping your own troops by handing out weapons with artificial recoil when they can have the same weapon without recoil.
Rapid-fire on a lasgun becomes a question of only powerpack efficiency and barrel heating, whereas on a conventional firearm you have to take into account: recoil management, ammunition efficiency and barrel heating.
lets not forget that the gun used in the trailer is used by inquisitorial personel so it doesnt have to represent standart issue equipment
considering that the Inq.troopers may be convicts, most likely taken from some sort of underhive where they were maybe exposed to large quantitys of auto/projectile guns
and he just chose a modefied version
My issue with this is we can throw explanations at it to make it plausible all day, but it doesn’t necessarily make it practical. To me it’s kinda like taking a perfectly nice car and putting square wheels on it, like, sure, it’ll work, but at that point you’re giving up all the advantages of round wheels. The situations where having it this way would work better are too few and far between to make it the norm, and I can come up with more uses for square wheels than I can adding recoil to a weapon that wouldn’t have it by default.
I mean I already don’t understand why anyone’d want to add more recoil to a weapon that already has recoil, adding some to a weapon like this where you could get away with no recoil is simply unnecessary bad design if it’s not a pure training weapon.
If we go the coolant route you could flush coolant via a feed system across/over the barrel and if coolant is vented anywhere, vent it left and right. That way the weapon is cooling even during full auto las fire.
But you DON’T KNOW THE TECHNOLOGY they have 
We also do not know if laser beam shots through the barrel of the gun at all. I mean the emitter of the beam might be at the end of the barrel.
So there will be no cooling issues at all so there would be no legendary recoiling cooling system.