Bolt rounds vs Astartes in fluff

[Ultramarine vet]

So, I'm attempting to write my own book. I'm hoping to be as realistic as I can with it.

 

So, bolt rounds are obviously really destructive. But just how effective are they against Astartes? How hard or easy would it be for a marine to shrug off a bolt round penetrating, say, their chest? I imagine it would be incapacitating the vast majority of the time? They explode within you, and I imagine your insides become an absolute mess. Even with all the added organs in a marine, I'm not sure they could just shrug it off. Though I know authors have wrote about marines surviving penetrating hits to the head.....so yeah.

 

I would appreciate all the insight and conversation from you guys!

[Jings]

Same rules as Orks afaik. They just get chunks blown off them until enough chunks are blown to take them down. 

 

Timestamped this video, should give you a good idea. 

 

https://youtu.be/FhULhHCk_D8?t=143

[Cleon]

So, obviously my personal take here and the setting does seem to vary with each story/author, but I think you have two scenarios here:

1 - a bolt round penetrating and either going all the way through, or failing to detonate, completely survivable for an Astartes and depending on where they might even be able to fight on during that engagement with some reduced effectiveness, in this case the torso is probably the best spot as they have so many redundant organs....

2- If it detonates then well, if its a limb that limb is shredded and useless, if its in the head that's a fatality, if it's in the torso then it depends what you mean by penetrate - if it penetrates their armour they still have the fused rib cage which could soak a lot of the detonation, but if it's inside that then best case he's hoping to hang on long enough for a dreadnought chassis to become available, worst case a kill on the spot.

[Noserenda]

In fluff i always figured Bolt rounds needed a solid hit to penetrate power armour, any glancing hit will either deflect or explode without fully penetrating, dead on in the chest? Its the thickest armour so would probably take a couple but its going to damage components.

[Firedrake Cordova]

Well, there's a whole series of books dedicated to the effects of bolt rounds on Space Marines. In all seriousness, Horus Rising is worth a read/listen, as it's not only a good book, but it does cover scenarios where Space Marines get hit in the body and head by bolter fire and similar. Obviously, whether they're "realistic" or not is another question, but it's what GW seems to think will happen ...

 

If you're looking for a real-world analogue to the bolter, have a look for gyrojet firearms - they use the same propulsion mechanism as a bolter (i.e. rocket-propelled), so they should behave similarly to bolter rounds in terms of how they fly compared to conventional firearms.

 

The other thing is, with high-velocity impacts you've not only got the damage caused by the piercing impact, but also cavitation and other damage to neighbouring tissue (skin is elastic, but generally the area around the wound tunnel is also damaged/torn leading to bleeding ... there was a TV program hosted by Will Willis which demonstrated this by firing rifle rounds at ballistic clay [a .303 rifle round knocked a 4" diameter hole in it], as well as on a ballistic-gel torso with "realistic" organs). Obviously, all of that is before you get to the fact that the bullets are substantially larger and go "bang".

 

TL;DR if it gets through the armour, it will be "unpleasant"

Edited November 3, 2021 by Firedrake Cordova

[Noserenda]

Oh yeah i think i misunderstood, if it hits flesh the marine is gonna get wrecked, might even do more damage as shrapnel ricochets internally off the non breached armour. The black carapace might stop a las round and all the chonk might help but bolters are major trauma for all, the only hope is redundant organs and maybe the Primaris furnace job.

[Domhnall]

Just had a wee search on gyrojet rocket guns, and you can get an idea of what they would be like*. I've skimmed through the video rather than watch it fully, but I might do later. 

 

 

So let's assume technology advancements remove their disadvantages. 

 

The rocket propellant doesn't seem to give it enough velocity to allow for much penetration or energy transfer, so on their own they wouldn't do that much damage, at best probably about the same as a standard round^. So if it's a soft target you'll get your penetration then cavitation damage as you'd expect, which is not nice. Against astartes armour, pretty much useless as there won't be the kinetic energy to penetrate. You'd only get penetration through weak spots or joints. 

 

Now, the real damage of bolt rounds comes from the fact they explode once in the target. So again, against soft targets, even if it doesn't penetrate, it'll cause massive internal trauma from the explosive shockwave. Against astartes armour, it can transfer some of that explosive energy though the plate which might cause an ouchy, but also damage the armour enough that successive rounds may get through. If it does get through, it'll be really really bad as the explosion will be rebounded about inside the armour causing even more damage. 

 

I don't think I've seen or read any depictions of a bolt round that does what I think a bolt round should do. Or even what they should sound like. It sounds awesome them having a boom as the rounds are fired, but in reality they should be pretty quiet as they leave the barrel as the rounds don't work like standard rounds (propellant goes bang in the barrel to launch the bullet out and the sonic boom that often accompanies it), instead the rocket will fizz as the speed increases and will give a sonic boom after that if it gets to that speed, and then goes boom! as the round explodes. So it should be Fizzz... Crack... BOOM! 

 

 

TL:DR In the fluff, they get bolts rounds wrong (in my opinion) all the time, and it's dependent on the rule of cool for the story. Because the fluff writers are not ballistics experts (and neither am I), they write what works for the story. 

 

 

* - In today's world, useless.

 

^ - EDIT: I'm now watching the video, and it mentioned that the round they used in the rifle version had more energy than a 9mm, and supposed to be similar to a .357 magnum, but this one didn't penetrate as well as a magnum as the casing was very soft. So I think it'd have more energy than an equivalent size round. 

Edited November 4, 2021 by Domhnall

[Karhedron]

In fluff i always figured Bolt rounds needed a solid hit to penetrate power armour, any glancing hit will either deflect or explode without fully penetrating, dead on in the chest? Its the thickest armour so would probably take a couple but its going to damage components.

There is plenty of Marine-on-Marine action in the HH novels. Where detail is described, it is normally either lucky shots finding a weak point (joints, eyepieces etc) or plates failing under weight of fire. A single direct hit will be unlikely to penetrate a chest plate but several hits might hammer their way through.

[phandaal]

40k is a made-up universe with made-up weapons, but if you are trying to be "realistic" then a bolt round going boom inside of a chest cavity would release all of its kinetic energy in addition to the explosion. As others have said, GW has given plenty of examples of what they think that would do in their Heresy books.

 

There is also the fact that joints are something of a "release" point for the force of a round as it goes through the body.

 

Without going into too much detail, a large enough round through a torso has a good chance of causing one or more limbs to fly off in addition to pulverizing the insides.

[Sword Brother Adelard]

I recall a mention of a Techmarine theorising early on in the heresy that gorgets would as a necessity need to rise considerably to protect neck seals now that bolt weapons were the primary threat, this is borne out by the armour designs on the whole, this was around the same time that they started to add the studs as ablative armour to take the bolt hits.

 

The inference being that armour was relatively proof against bolt shots, but soft seals were wholly inadequate, and would need more protection.

[Iron Father Ferrum]

I don't recall studs ever being explained as extra armor; they're used passed off as bonding studs (ie, giant rivets) to hold layers of armor plates together.

[BloodyB]

If a bolt round goes off inside a marine, it is liable to cause a casualty. Possibly not death, given an Astartes' healing capacity, sheer toughness, bodily self-control and the presence of advanced medical aid both inside the armour and available to the apothecaries of the chapter. Honestly, a bolt round detonating inside a Tyranid Hive Tyrant is liable to be a casualty too, a 20mm high explosive cored round is quite likely to put anything into critical care.

 

Think about the weapon and what we have to compare it to: it may function in a similar manner to a gyrojet weapon, but the actual projectile is more inline with a GAU Avenger Gatling gun, commonly used to shred tanks and weapon emplacements on today's battlefields. The very fact that space marines regularly survive these wounds is honestly quite terrifying.

[Ultramarine vet]

I know a great deal about the HH books, bit haven't necessarily read a lot of them though and through, which I should do anyway honestly. I'll read a good few of them before I go much further in my own book

 

I reckon if a bolt round penetrates AND detonates in your shoulder, your arm is probably going to be shorn off, I imagine. Very similar to that, I suspect that the same kind of hit to the knee would most definitely leave you without half your leg. Even if the limb isn't detached, at the very least the limb should be useless due to all the nerve damage, I highly doubt it's even possible in the slightest for it to work.

[Sword Brother Adelard]

I don't recall studs ever being explained as extra armor; they're used passed off as bonding studs (ie, giant rivets) to hold layers of armor plates together.

Oh quite. Ablative was a description I saw on one of the Wikis, and I agree it would help in that way, they would help with taking the hits and deflecting the round somewhat.

[StraightSilver]

There's also the fact that bolt rounds are "mass reactive", which means they only detonate after they have penetrated. So a bolt round that is deflected by armour won't explode, but if it manages to penetrate it will.

Bolters are also 2 stage weapons, so have a propellant and conventional percussion charge, so a bit different to today's gyrojet weapons.

 

I would imagine that a bolt round would do some pretty significant damage even without exploding, but if it got through power armour could still be devastating even to an Astartes.