Rip in piss. Also, I don't think eldar have any shotguns other than the scatterlaser which is a vehicle mounted big gun and currently on the falcon and currently rapid fire because they assumed it was like a machine gun.
Marines carry shotguns under certain circumstances, deathwatch specifically. The game isn't too accurate to canon sometimes and something like this would be fine if it were added.
Umm... The scatterlaser is a rapidfire laser. A shotgun wouldn't have the range of a heavy bolter, nor would it be mounted on vehicles
On that note though, wouldn't a shotgun completely invalidate Eldar? Since their optimum range is about 12m...
Shotguns aren't used by Marines because they are just not useful. You are increasing the area of impact but reducing penetration and bullet damage. Against armored or thick-skinned enemies, this is not recommendable. The benefit of concentrating the "Blast" on point-blank range (What shotguns are known the most for in video games) is also not very useful when compared to say, a Bolter that not only gets that, but also explodes on impact. Deathwatch marines use them occasionally for some very specific things, almost always involving special ammunition to accomplish a very specific task. Like boarding a Space Vessel and not wanting it to blast a hole on it (which is funny since you are basically downgrading your firepower). But overall speaking, they are inferior to a regular everyday bolter by a large margin. Here are the stats of an Astartes Shotgun from the Deathwatch RPG: Astartes Shotgun Range: 30m Fire modes: Single Shot/2 Semi Auto/– Damage: 1d10+9 Damage type: Impact Pen: 4 Clip: 18 Reload: Full Turn Traits: Reliable, Scatter Here is the Bolter by comparisoin: Astartes Bolter (Godwyn): Range: 100m Fire Modes: Single Shot /3 Semi Auto/– Damage: 1d10+9 Damage Type: Explosive Penetration: 4 Clip 28 Reload: Full Turn Traits: Tearing Tearing means you roll damage twice and keep the best result. Scatter adds a dice of damage when doing a point back attack depending on successes, but doubles all armor used against it at Long or Extreme Range. Reliable mean it's unlikely to jam. Explosive damage is preferred over Impact when it comes to wounds. On almost all situations, the Bolter is better. You get 3 shots in one burst at all ranges, do the same "Base Damage", but also do more consistent damage. Meanwhile, the Shotgun has a short range (The same as the Pistol range in this case), gets some increasing penalties at longer ranges, and only does more damage on a specific case; which is shooting at point blank on an excellent hit (4 Degrees of success or more) to outdo the Bolter. The point blank case isn't very useful, because it is basically melee range. It's just not worth using as your main weapon because it leaves you lacking in medium-long range fights and only being marginally better at close range. It does make for a handy backup if you are using something else tho, but we don't get to carry two basic weapons in EC. And really, I won't even bother making the comparison to the Storm Bolter, which is just obscene. A Shotgun on EC would be competing for the same spot as it, and that is just not a fair match.
Deathwatch kill teams are as far away from your standard chapter as it can get and we don't even have them in game.
Even in Deathwatch, shotgun is still outclassed by Bolters, who also got shit tons of possible special ammunition to kill their enemies. The shotgun is such a specific weapon that shoot so few special type of ammunition the bolter cannot fire, like stun ammunition, those kind of thing, it's pointless to have it on you. If the game was fluff you would have a kind of shotgun in the melta gun, who is normally a overheated beam that fire in a second, not a constant flow of fire, but my theory is that they turned it into the actual version to avoid the problem in Space marine multiplayer where Melta gun was a must as it was a one shot weapon.