A Boltgun, also known as a Bolter, is a large-caliber, deadly weapon that on Ancient Terra would have been called a 'cannon'.
It fires special ammunition with four gas vents at the rear; the moment it leaves the barrel, the primer ignites the propellant, and scorching flames erupt from the four rear vents in a spiral, causing the Bolt to spin during flight rather than becoming a Brownian motion projectile.
It has been the most iconic weapon in the entire Imperium of Man since 30K.
As for why it isn't the Chainsword, it's because even the Eldar have those. (╯‵□′)╯︵┻━┻
Logically, this design should result in lower recoil because the bullet accelerates after leaving the barrel.
But this is a dark and grim world where monsters roam the streets, and close-quarters combat often doesn't allow the Bolt enough distance to accelerate.
To prevent the Bolt from hitting the enemy like a pebble at extremely close range with no effect, effort must be put into the muzzle velocity.
The cost, however, is that this weapon is large, heavy, and has astonishing recoil; an untrained ordinary person could very likely have their skull smashed by a dropped Boltgun before they even pull the trigger and kill the enemy.
Thus, Boltguns are also categorized:
1-inch (25.4 mm) Heavy Bolter.
.77-inch (19.6 mm) Astartes Boltgun.
.66-inch (16.8 mm) Godwyn-Diaz Boltgun, also known as the Sororitas Boltgun.
There is also the .455-inch (11.6 mm) Navy Blast Pistol, which is smaller than the Sororitas Boltgun but maintains its power due to its longer ammunition.
And the .38-inch (9.6 mm) 'Commissar Boltgun,' the most common mortal Boltgun in the Imperial Army, often found in the Bolt Pistols wielded by Commissars.
'+Activation: machine soul's Favor+'
'+Energy: 3/6+'
'+Psionic: 2/6+'
'+Corruption: 5/6+'
'+Soulfire: 4/40+'
Buzz—
The console screen, which required Adeptus Arbites retinal authentication to activate, lit up.
'++Purge Protocol Activated++'
'++Self-locking onto Enemies of the Imperium++'
'++Locked++'
'++Fire++'
*BANG!* *BANG!* *BANG!*
The flashing loyal muzzle flashes illuminated the dim storage yard.
Facing the sudden onslaught, the Chaos Spawn's Warp shield couldn't withstand the storm of Heavy Bolter fire for even half a minute.
The monster roared in astonishment, its deafening cry shaking the ground, slime splattering everywhere, abandoning the chance to kill the mortal Arbiter before him, and immediately fled clumsily to dodge.
But even so, its massive, corpulent body was hit twice by Heavy Bolter rounds, and two huge holes immediately appeared on the Chaos Spawn's limbs and body, blue-purple gore spraying tens of meters away.
"Woah."
Horatio stood in the center of the vehicle's Boltgun control panel, his thumb pressing firmly on the Boltgun's firing mechanism.
Thanks to the loyal machine soul's assisted aiming and the mounted peripheral cameras, Horatio could clearly appreciate the powerful, immense might of the Heavy Bolter.
If a human had been hit, their entire body would have been blasted into a mangled mess.
"How can this be... How can that kid activate the Adeptus Arbites's specialized machine soul... This... This is impossible!"
Shayev raised his arm to block the Bolt fragments from splashing onto his face, and through his fingers, he saw Horatio sitting in his seat, dangling his long legs, leisurely watching the Chaos Spawn flee in disarray from the Bolt fire.
A suffocating rage, like being cuckolded, welled up from his heart, but he was helpless.
The Chaos Spawn hurriedly pounced on a corpse to devour flesh and blood, but less than a second after landing, it took a Bolt round, its spherical body stumbled, and it was so frightened that it only dared to cower behind the old, broken container, licking its wounds.
Hiss—
The Heavy Bolter stopped firing, and the short, thick barrel, coated in a layer of white ash, hissed with intense heat.
'++Ammunition low, please reload++'
That's the downside of the Heavy Bolter; the ammunition is too bulky. Even with a belt feed, it can't hold many rounds, and it stops firing before you've had enough fun.
Horatio saw the red warning on the screen and immediately took Shawei Arbitrator's spare Enforcer Shotgun from the gun rack behind the seat.
Hearing the gunfire cease, the Chaos Spawn emerged from behind the container with heavy steps and charged towards Horatio, who was sitting in the armored vehicle.
"Sorry, but I'm borrowing your precious toy."
Horatio pumped the shotgun, chambering a massive 10-gauge round.
The heavy, rough footsteps grew closer and closer. Horatio could see through the thermal imaging that after devouring multiple corpses, the massive, spherical creature, now nearly 3 meters tall, was charging at him like a giant bowling ball.
Horatio stepped out of the driver's seat, stood at the front of the vehicle, raised his gun, aimed at the hideous, cracked head, and stood ready.
Closer… 15 meters… 10 meters… 8 meters.
Bang! The massive Enforcer Shotgun spat fire. This rapid-fire shotgun was a great weapon against unarmored units like the Chaos Spawn.
Five consecutive shots tore into the Chaos Spawn's front, turning it into a bloody mess.
But Horatio also discovered a terrifying reality—where was this guy's weakness?
The shotgun blasts sent flesh and blood flying, but they couldn't stop it from continuing its charge.
Moreover, after being hit, it only roared; its body showed no sign of retreating, as if controlled by some unseen thread, yielding to the most primitive instinct for slaughter.
Soon, all ten shotgun shells were expended. Besides making the Chaos Spawn look even more disgusting, they also blew off some extremely dangerous tentacles, but ultimately failed to end the monster's life.
The Chaos Spawn let out a horrifying roar, and disgusting slime splattered from its gaping maw.
Horatio swung the empty shotgun at its head, smashing its ugly cranium inwards.
Then he leaped, rolling to evade the huge pincer swinging towards him.
Before he could stand up, terrifying spines resembling tentacles on the Chaos Spawn's back lunged towards his chest.
Just at this critical moment, a graceful figure leaped, severing the tentacles in mid-air.
"Get up quickly!"
Horatio was pulled to his feet by Farida, who gripped a short sword glowing with a faint blue electric light.
[Power Short Sword?!] Horatio was surprised at first, but then, considering her identity, it wasn't surprising that she possessed such an expensive weapon.
"This monster seems unable to see me. You distract it, and I'll take it down from behind!" Farida looked at Horatio.
"You… are truly an Untouchable?"
Psionic power is like a magnet, with both positive and negative poles, and an Untouchable, or soulless one, is precisely that negative pole.
Like psionic power, it is naturally present in only a small number of people, the bane of all who rely on the power of the Warp, and unseen by demons and the unclean beings of Immaterium.
If the soul is a spark of a star in Immaterium, then the soul of a soulless one is a black hole that terrifies demons.
Farida said nothing, tacitly confirming Horatio's guess.
The girl immediately ran to the side and rear, while the monster's aggro was fully drawn by Horatio, who then took a whip-like strike.
Horatio braced his legs and swept the gun horizontally.
Clang! A sharp sound, like thunder, rang out. The gun body broke, scattering like falling flowers as parts rained onto the ground.
Horatio retreated several steps, then braced his feet, stopping, gasping for breath.
Even with the bionic limb, the upper arm was still flesh, numb and aching from the violent impact, without sensation for a long time, his entire iron hand almost instinctively resisting the fierce attack.
The Chaos Spawn gave him no chance to breathe, agilely dodging successive attacks. If he wasn't careful, his flesh and blood limbs would instantly be torn and stripped away, becoming sweet nourishment for the fleshy orb.
Although the Female Hunter-Duke had begun to act, Horatio disliked being passively beaten; he didn't want to entrust his life to others.
Taking advantage of an opportunity to duck and dodge, he bent down and picked up a fallen Arbiter's shock maul; the massive hammer head at the tip of the maul pulsed with surging electrical energy, full of deterrent power.
Although this deterrent was useless against the Chaos Spawn, being armed was better than being empty-handed.
Suddenly, he was pulled into a dark vision, and two skills simultaneously glowed with a golden aura before his eyes.
[Is this… a combo skill?]
Farida's agile and strong long legs allowed her to quickly outflank the monster. Enhanced by her power armor, she leaped to a height impossible for ordinary people, gripping her power sword, which was filled with a disintegrating field, with both hands, and as she descended, she plunged the short sword fiercely into the top of the Chaos Spawn.
"Roar!" The monster let out an unprecedented roar; if the active noise-canceling device on their helmets hadn't automatically activated, their eardrums would surely have ruptured by now.
Although it couldn't perceive an Untouchable standing on its back, the excruciating pain made it twist its corpulent body wildly.
Suddenly, disgusting cysts appeared on its back and began to swell larger and larger.
"Careful! Get away!" Horatio shouted at Farida.
Farida knew something was wrong and immediately leaped towards Horatio's direction.
The cysts soon exploded violently, and bizarre blue-purple slime splattered everywhere. It seemed to be an instinctive reaction after an allergic reaction to the Untouchable; wherever the slime touched, blue feathers and twisted tentacles slowly grew.
The violent explosion sent the leaping Farida flying, and her sword also fell onto the monster's back.
Horatio smashed away a giant pincer swinging at his head and opened his right hand to catch Farida, who had been thrown back by the impact, pulling her into an embrace.
"Ugh!" The weight of this girl plus her light power armor, hitting Horatio at that acceleration, made him grunt in pain.
"Hiss!" Farida frantically tore off the communication array from her headset.
"Damn it, what is that awful sound? External communication is completely dead; I can't send out any distress signals."
Farida forcefully shut down the communication device that was emitting strange laughter and said.
"It's fine if they don't come. If this gets out of hand, I don't want to win only to be executed by an Inquisitor."
Horatio glanced at the beautiful woman in his arms and said gravely, "Go tend to the wounded. I'll handle the rest."