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Lynata wrote:
Though that is pretty stupid, to be fair. Even with recoil being negligible, a stock always increases accuracy. But for the Space Marines I suppose there's no room for it, anyways. Must be hard enough as it is wielding the gun with that much armour in front of the chest. Limited mobility for the arms and all that.

I suppose the Astartes equipment and the armour (and the helmet) itself might compensate for it.

Bolters fire many diffent kind of bolts.

Some explode on impact while other explode after penatrating. Some even explode before striking the target.

Some are acid filled. Some are high explosive. Some are silent rounds.

They fire like machineguns in the other media because its more intimidating than the actual bolter description.

Once upon a time Bolters had no recoil as they fired self-propelled rockets. Basically they were rapid-fire RPGs.

I never understood the "roar" or a bolter. I kinda imagine they sound like large paintball markers.

The helmet has been, for a long time, described as incorporating an "autosense" link between the helmet and the bolter itself--essentially "drawing" a reticle for the Astartes where the bolter is aimed.

Kanluwen wrote:You actually have to look for older models. The older "boltgun" styled guns did have stocks.

Phew, you're right - found some pics in the web. Ironically, those were said to be Marine bolters, heh.

But what bikes do you mean? The Astartes ones?

SomeRandomEvilGuy wrote:I suppose the Astartes equipment and the armour (and the helmet) itself might compensate for it.

Yeah, even if not all bolters may come equipped with the autosense link - also, I guess the massive pauldrons do lend themselves well to simply resting the stub-butt against it. Or possibly "locking" the arm, as Kanluwen mentioned. For the Marines, aiming their gun is probably just like pointing a finger, whereas normal humans at least have to deal with the immense weight of the weapon.

What other bikes would I mean?

The Scout Bikers are done up using a different body and bits.

After never having seen those 2E Marine bolters before, I better ask to make sure.

Thanks for clearing that up. Learning never stops!

Ironically, I'm avoiding learning right now by posting here instead of doing homework for a computer class...

But yeah. Bolter stocks have existed, they just don't so much anymore. I think they swapped the looks on Guard ones so it's more recognizably a "bolter" at an easy glance.

Thatguy91: As always you picks your source but the overwhelming bulk going way back describes the standard Bolt as explosive (see Lynata's link). The only source that I can think of that consistently describes Bolts as non-explosive is James Swallow's novels (...).

In terms of the why, and comparing with hollowpoints, instant incap's hard enough with humies, let alone most of the gribblies in the 40kverse; and it's even more important against them, especially when grossly outnumbered as Astartes will tend to be.

A Bolt's large diameter and heavy but way too slow for rapid energy transfer (lots of momentum but not lots of KE). Simply making a wide hole in something doesn't stop it very quickly (unless it hits something in the central nervous system). Tissue is highly elastic so you get a temporary cavity with not much tissue damage which then contracts leaving a permanent cavity (IIRC ~70% the width of the projectile).

To get a bigger permanent cavity (than a hollowpoint of that calibre would produce):-

1 Dump KE into the tissue quickly and perforate the expanded tissue with energetic fragments (inert Bolt too slow for this);

2 Dump KE into the tissue so quickly that the shockwave exceeds the speed of sound through the tissue (overcoming its elasticity) - the temporary cavity in this region becomes permanent (inert Bolt way too slow for this). This method will also shock the fluids in the region causing rupturing of blood vessels and so on, and is more likely to produce the 'hydrostatic shock' distant effects therefore;

3 Place a propellant (not high explosive) in the projectile with enough force to shatter and throw out the projectile's walls (but not set up a supersonic shock wave) and you get > method #1;

4 Place a high explosive in the projectile (which breaks and throws out the projectile's walls) and get >> method #2 plus >>> method #1, plus thermal and chemical effects, plus an extremely versatile round able to damage many types of different targets (in conjunction with the armoured tip).

It really is the one shot stop (against most things, and just as well given how temperamental they are described as being) brutal, horrific, terror weapon that the fluff often describes it as (why Commissars get Bolt Pistols); and that most games notoriously don't match in stats or effect for balance or censorship reasons (see the movie Space Marines article from back in the day where the Bolter should really be an autocannon, in terms of stats).

* * *

As to RoF, I haven't ever come across any figures. The only RoF numbers I've seen for 40k are for the generic Lasgun and Auto Pistol in the Uplifting Primer. These weapons are often described as being able to hose away (especially Auto Pistol, that being its raison d'être) and their stated 'full auto' RoF are (respectively)... 220 shots per minute (cyclic) and... 150 shots per minute... slower than contemporary semi-autos....

I'd expect the Bolter to cycle slower than this for simple mechanical reasons (longer round, bolt and most of the rest of the action larger with more inertia). It'd also make sense given how formidable each Bolt is (neither target effect nor suppression fire requires high RoF with such rounds), and how temperamental the weapons are described as being, plus the horrendous recoil that's often mentioned.

Melissia wrote:

Thatguy91 wrote:Basically what a hollow point round will do.

Except... better.

Why does everyone act as if all wounds are equal?

Not at all what I was trying to imply, sorry if my post was confusing. What I ment was that I think the rounds act like a hollow point in that they expand, explode, whatever, inside of the target rather than the second of impact. Bolter rounds definitely have a small explosive charge in them but not a grenade-like charge nor a HE charge. Thats why I was trying to compare them to hollow points as I think they would behave similarly. Not entirely sure what I was trying to argue with that last post.

Psienesis wrote: However, when a single bolter round is capable of blowing through most body armor worn by the staggering majority of your enemies, penetrate their bodies and then explode inside them... you don't really need to shoot someone twenty-five times to kill them.

Majority perhaps, but not all. Why not include a fully automatic setting? We're talking about Astartes here, not humans. They have the training and presence of mind to only use automatic fire when it is appropriate.

Thatguy91: Aye, frangible projectile's probably a better model, but with a charge driving the fragments for extra penetration - at the very least (bit more if you find the fluff of folks being blown apart and viscera everywhere more credible) - and with an armour piercing tip that will continue to penetrate deep into larger targets after the detonation and fragmentation of the projectile's body.

Primarily intended to detonate within the target but will still have decent penetration against good armour that resists it with the charge going off outside and driving the tip through (as said).

Good round.

One of the more believable and realistic bits of 40k kit (just take the heinous recoil and depleted deuterium core with some salt and walk by whistling...).

Which recoil? No GW source actually ever talks about it - it's just that some novel authors thought it would be cool were that the case. For what it's worth, I can relate. In pop culture, recoil has come to be regarded as a measure of how powerful a gun is, even though this is a very "gut-feeling" kind of thinking.

But yes, the "depleted deuterium" bit is fun stuff. I've seen someone trying to excuse it as condensed ice or something, but not even I am touching this with a 7-feet-pole, and usually I enjoy finding excuses.

Lynata wrote:I've never, ever seen a GW miniature that features a bolter with a stock.

The plastic boltguns with which accompanied the metal body/plastic arms Mk 7 Marines of 1st and 2nd Edition had stocks. Why they did, I know not, since assembling an armed Marine required trimming the stock straight off.

To return to the general question: who cares? The bolter round's core of 'depleted deuterium' makes no scientific sense whatsoever, but Warhammer 40,000 isn't a hard sci-fi setting.

In regards to what Riplikash was saying in the beginning about the explosive core, and exploding, is it maybe like the XM25? Maybe setup to the SM's targeting in the helmet, and then exploding after a certain distance? That's just me trying to make sense of it, i'm not sure about any official fluff in this regard.

Honestly I think folks make a Bolt round out to be way more complicated than it is, and the bulk of the fluff is pretty explicit in the basic principles. It doesn't have the complicated fusing system of the XM25, since it isn't a grenade designed to airburst at a pre-determined point for sneaky area-effect damage. It's just a hard-hitting direct fire weapon, like our regular, old school, armour piercing high explosive cannon projectiles (in complexity and principle).

Comparatively small charge kicks projectile out of the muzzle and (presumably) provides the gas necessary to cycle the weapon. Projectile's rocket ignites and provides the lion's share of the velocity (so most of the momentum change happens externally to the gun, so not much recoil) and a consistently flat trajectory whilst burning.

It hits something hard (ie with mass) which causes the mechanical detonation process to commence ('mass reactive' - probably designed such that a window wouldn't provide enough resistance to trigger anything) such that there's a miniscule (standard) delay between impact and detonation, allowing the projectile to get deep into the vitals of an averaged roughly humanoid target wearing averaged armour before the explosion.

There's no electronic, digital monkeying about with complicated fusing, since it's a direct fire over-killer with enough yield and ability to send numerous controlled follow on shots rapidly down-range that it doesn't really matter if it detonates a bit prematurely because it hit soft cover, an ammo pouch or an arm first, or detonates a bit later because the target had softer armour and tissue than the averaged figure used. IoM likes standardisation and simplicity.

I've got harder figures knocking around somewhere but just for example:-

Suppose the Bolt will on average be travelling at 300 m/s after it has penetrated average (Flak, say) armour, and is penetrating average humanoid tissue (mean of bone and... some really squishy organ... spot the biologist...), rocket still burning. For the sake of simplicity we'll say that it was also the same speed through the armour, and the armour is 5cm thickness. You want detonation to occur (say) 15 cm into the target itself, with the big dense tip continuing to achieve the FBI recommended 18" minimum total. Make your detonator be triggered by a threaded pin or something that always takes exactly 0.00067 sec to go from projectile initial impact to full detonation and you don't need any additional finicky fuse or whatnot.

Simple and rugged and if circumstances make the actual detonation an inch or two before or after the optimal average figure, then that's why you've got a big fethin warhead (and at least semi-auto RoF in a low recoil [for my money] weapon, and 20-30 round magazine).

Astartes need weapons that drop fools instantly with as much noise and gore as possible whilst they keep the momentum of the assault up - they don't have much use for grenade launchers, especially fiddly and faffy ones that you have to stop to reprogramme.

* * *

EDIT: Summary: Best model is a short ~20 mm armour piercing high explosive cannon projectile (penetrates then explodes, not a grenade) with rocket propulsion, and a small charge just to kick it out of the weapon and cycle the weapon. Penetrates first because the warhead is monstrous inside the target but really feeble outside it.

tsz52 wrote:Comparatively small charge kicks projectile out of the muzzle

Quite a large charge, actually, as it is instantly lethal at short range as well as long.

Melissia wrote:Quite a large charge, actually, as it is instantly lethal at short range as well as long.

Though it has been said that the projectile leaves the barrel at low velocity, only taking up speed after it is free of the weapon.

I suppose it comes down to (a) what is "low velocity", what is (b) "short" and (c) how "lethal" does it have to be. Or even more importantly, how effective is the miniature rocket at propelling the bolt to "lethal" velocity. As always, a matter of interpretations. The way tsz52 described it, it does match GW's version of the fluff.

Lynata wrote:Though it has been said that the projectile leaves the barrel at low velocity

I don't think you ever provided a canon source to this, but even so, nowhere in recent lore has it been depicted as less lethal or able to penetrate less armor at point blank range.

Being of a lower velocity would be less lethal as well as less accurate. This does not match GW's version of the lore.

Melissia wrote:I don't think you ever provided a canon source to this

That bit was in the 2E Wargear book, which had rather extensive descriptions of a lot of stuff. To be fair, I've not seen it printed anywhere else either - that said, such details have always been thrown all over the place in 40k, so I'd not be surprised if it also shows up in some White Dwarf issue or another obscure source. But if so I haven't stumbled over it yet.

Melissia wrote:Being of a lower velocity would be less lethal as well as less accurate. This does not match GW's version of the lore.

Only when we assume that the miniature rocket is unable to kick the projectile to full speed within the blink of an eye. Yes, it may sound crazy, but this is how it was described - it's, simply put, 40k science at work.

For what it's worth, the Deathwatch Kill Team rules in WD #305 also mentioned that Stalker-bolts are subsonic, which means they would have to travel at a velocity lower than ~340 m/s - at maximum speed without, according to the fluff in the very same article, loss of lethalty. Maybe the "diamantine tip" of a bolt round has monomolecular edge treatment or whatever - after all, penetration does not necessarily depend on a projectile's velocity and mass alone, but can be influenced by shape and material as well. Also, penetration does not have to happen 100% of the time, anyways, neatly explaining why not every bolter hit is a guaranteed kill even when facing IG.

I think my own opinion falls somewhere between yours and that of tsz52 in that I compare the initial discharge to a contemporary shotgun - this would fit the aforementioned 340 m/s nicely and be quite lethal at point blank already, with any sort of recoil being rendered a non-issue by the gun's own heavy weight as well as any internal mechanisms (such as, for example, the blast compensator in the 3E rulebook's bolter schematic).

There's room for a lot of speculation/interpretation. Which is probably why their description differs from novel to novel - though I still think that any mention of recoil in a story happens largely due to the "rule of cool" in various action movies. And I will admit that find myself constantly torn between the aforementioned technical description and my own affinity for said rule, too. Fortunately, everything is vague enough to easily allow for a personalized balance between the two.

(fun fact, the necessary push to achieve an acceleration rate of 340 m/s² for a 0.25 kg projectile is approx. 85 newtons - this can be achieved by a modern day class G model rocket engine - the rest is simply a matter of miniaturization)

BeRzErKeR wrote:Personally, I've always pictured Space Marines using their bolters on single fire or short bursts and double-tapping their targets. By the time he has power armor and a bolter, a Space Marine has superhumanly keen senses, decades (at a minimum) of combat experience, psychological conditioning (and potentially advanced brain surgery) to repress fear or excitement reactions that commonly throw off accurate shooting,.

I dont think so, In savage scars it shows that space marines can go into a beserker rage at the drop of a hat.
Alsso i think they do have to power to go rabid fire and full auto. Its just the space marines dont us iit that often. The prefer to go with short bursts to prevent to much recoil.
Also i dont think power armor does much. Scouts, Some IG and others us it just fine w/o power armor.

hotsauceman1 wrote:
I dont think so, In savage scars it shows that space marines can go into a beserker rage at the drop of a hat.
Alsso i think they do have to power to go rabid fire and full auto. Its just the space marines dont us iit that often. The prefer to go with short bursts to prevent to much recoil.
Also i dont think power armor does much. Scouts, Some IG and others us it just fine w/o power armor.

Certainly some Space Marines, due to defective geneseed or Chaos corruption, are somewhat uncontrolled in their emotional reactions. But those aren't the majority. The process of creating a Space Marine explicitly includes psychological conditioning (or brainwashing, if you prefer the term) to suppress fear; it's easy to imagine that they might also, while they were at it, remove the physical, uncontrollable reflexes associated with ANY strong emotion, since most of them are a detriment on the battlefield. When you get excited or nervous, your hands tend to quiver, your twitch reflex is magnified, you sweat more (which can be distracting) and you tend to move too fast and over-correct for mistakes. Suppressing those reflexes would be an enormous advantage; essentially, you'd end up with a soldier who was 'in the zone' at all times, functioning at peak performance even under stress. Since the Space Marines are specifically designed to be as effective on a battlefield as the human body can support, I would think that the engineering the Space Marine physiology undergoes would significantly reduce or entirely eliminate most of the things that make accurate and controlled fire so hard for humans (compulsive trigger-jerking, rapid or irregular breathing, adrenaline shivers, etc), even if it doesn't make them not FEEL the emotions associated with those problems.

It's canonical, I believe (though I cannot quote a source at the moment) that Space Marine power armor includes auto-senses and even a direct visual link to the weapon the Space Marine is carrying; that being so, a suit of power armor + the Black Carapace should, indeed, increase the accuracy of a Space Marine significantly. Of course, perhaps they're simply so experienced and naturally accurate that it isn't important in most situations. Combined with their long and frankly brutal training regime, perhaps a full-fledged Space Marine barely even uses his armor's auto-senses, instead snapping off shots from the hip based off instinct just as accurately as a human who takes the time to aim.

Bolters are, in numerous pieces of fluff, depicted as firing either very rapidly in burst mode or in full-automatic. I don't doubt that Space Marines have that capability, since in some situations it would be very useful and Space Marines are supposed to be able to prosecute practically any fight against practically any enemy. If you're facing an Ork horde charging straight at you in a solid mass, accuracy is secondary to rate of fire; you WILL hit the Orks, you just need to put rounds downrange. But I (personally) believe that in most situations, single-fire or perhaps two or three round bursts is far more appropriate, and probably far more commonly used. Most of the time, as I said, Space Marines are fighting humans. Normal humans don't need to be hosed down with bolter fire to die, one or perhaps two in the center of mass will do just fine. Why expend more of the Emperor's holy ammunition when you don't need to? Kill what needs killing, get the job done; Space Marines may be fanatical Knights Templar, but they are also disciplined and professional soldiers.

There is mention of a 'kicker' charge in the ideo describing the bolter. That 'kicker' charge could well provide a decent (albeit brief) burst of suitable velocity before the main rocket charge fired, providing the final boost to speed and sustaining that speed for the duration of the projectiles life.

This is a big difference from the rocket charge only gyrojet which as been known to be stopped by a piece of cardboard over the muzzle of the gun.

Lynata wrote:For what it's worth, the Deathwatch Kill Team rules in WD #305 also mentioned that Stalker-bolts are subsonic, which means they would have to travel at a velocity lower than ~340 m/s - at maximum speed without, according to the fluff in the very same article, loss of lethalty.

Those are specialist rounds, which have a different design than normal bolter rounds and are also more expensive and harder to procure.

Also, since the primary kill mechanism of the bolter is the explosive power, rather than ti's velocity, subsonic isn't quite as big a problem as may be thought. As long as the shell hits going fast enough to penetrate into the target before detonation, the results should be about the same.

Jefffar wrote:Also, since the primary kill mechanism of the bolter is the explosive power

If a bolter shell doesn't penetrate flak armor, it's not killing a guardsman. Flak armor is specifically designed to work well against small blasts and shrapnel. A bolter shell exploding without penetrating flak armor will, at best, cause a broken rib or two, probably just bruising more likely.

Melissia wrote:

Jefffar wrote:Also, since the primary kill mechanism of the bolter is the explosive power

If a bolter shell doesn't penetrate flak armor, it's not killing a guardsman. Flak armor is specifically designed to work well against small blasts and shrapnel. A bolter shell exploding without penetrating flak armor will, at best, cause a broken rib or two, probably just bruising more likely.

Unless the shrapnel shreds his unarmored face. . . or rips up his arms and severs an artery. . . or cuts his (again, unarmored) throat. . . or the bolt bounces downwards, explodes between his legs, and gives him a groin full of red-hot metal.

You see where I'm going. Imperial flak armor works well against small blasts, yes, but I would think that a single bolt shell would do pretty damn serious damage even if it hit at the wrong angle and ricocheted off the armor. If it buried itself in the armor before exploding but without fully penetrating, now, the Guardsman might not be badly hurt but his armor would be ruined around the point of impact. Time to run away!

So far the most accurate representation I have seen in bolter media was in fire warrior, the Tau carrying the weapon could fire 2 shots in a row(burst?), this could be done in succession, but with a pause in between, when I think of a bolter this is how I think of it firing. A Space Marine could probably keep up a higher rate of fire that a simple Tau, but why waste the expensive ammunition? You are a super human, your gun can put just about ANYTHING down in those 2 shots (Anything your size anyway). Marines might never know what might be coming on a hostile planet, or how much ammunition they might require, they make every shot count, because they are the best.

BeRzErKeR wrote:Unless the shrapnel shreds his unarmored face

The weapon does not produce much shrapnel. It is not a fragmentation grenade. Furthermore, in many models the face IS covered by flak armor, via a mask-- and flak armor is resistant to fragmentation weapons.

BeRzErKeR wrote:or rips up his arms and severs an artery

The weapon does not produce much shrapnel. It is not a fragmentation grenade. Furthermore, the arms are covered by flak armor-- and flak armor is resistant to fragmentation weapons.

BeRzErKeR wrote:. . . or cuts his (again, unarmored) throat. . .

The weapon does not produce much shrapnel. It is not a fragmentation grenade. Furthermore in many models the throat IS covered by some form of flak armor-- and flak armor is resistant to fragmentation weapons.

BeRzErKeR wrote: or the bolt bounces downwards, explodes between his legs, and gives him a groin full of red-hot metal.

The weapon does not produce much shrapnel. It is not a fragmentation grenade. Furthermore, the groin is covered by flak armor-- and flak armor is resistant to fragmentation weapons.

Flak armor is designed SPECIFICALLY to protect against shrapnel and blasts. Using a fragmentation effect is the least efficient way to get through flak armor. Lasguns are more efficient at getting through flak armor than fragmentation. Your point is moot.

That said, any explosive device covered in anything will cause shrapnel. Anti-personnel devices simply produce more, increasing the likelyhood of hitting anything even over a distance of several meters. I would say that the fragmenting metal casing of any bolt round being shattered on the target's armoured chest does pose a certain risk to see the poor guy's chin punctured, or more. Though I think the risk for injury is far greater than actual death (if medical attention can be secured).

Also, not all IG regiments actually wear flak (or even any) armour, though this is admittedly besides the point.

Getting a bit more into conjecture, and less consistent sources, now but:-

Melissia: Even a comparatively small kicker charge can be lethal at the muzzle, the Bolt having high sectional density with a fairly pointy tip. It'll hit with all of the extra mass of its unexpended propellant.

And don't forget its dual purpose nature, with the warhead being behind the tip: if Flak stops it, the explosion's effect is still focused into the target by giving the tip a shove forwards (two chances to penetrate), probably whilst the armour is still being pushed and stretched by the initial impact, which will be further stretched and torn by the shock and shrapnel that also goes forwards along with the tip.

[EDIT: Yup, it isn't a fragmentation grenade. But there will still be some shrapnel/fragmentation. And just as explosive and shrapnel effect drops off massively with increased distance, it also increases massively with decreased distance... especially if in direct contact where the target itself (rather than mere air) conducts the shockwave.]

If that still doesn't go through then it's certainly prepared the target nicely for the second Bolt incoming.


Lynata: Sources eh... what are they like?! Anyroad, this is my take:-

Recoil: Not so much a large reaction force (not much initial projectile momentum and heavy weapon, and muzzle brake etc) but the action is big and heavy with a long stroke, and the recoil-axis is pretty high, so there's a lot of mass moving suddenly backwards and forwards high up which makes the weapon a bit jumpy and lively in your hands.

Velocity: Can't find my sourced crunchy numbers but I'd expect standard Bolts to be either defo subsonic or >Mach 1.3, since being transonic is inefficiently draggy and plays hell with accuracy. Since mass, warhead and large diameter seem to be the order of the day, then I'd imagine that standard Bolts avoid being pushed through the turbulent transonic region altogether, to get that bit more range out of the propellant efficiently. And the short stubby cone (as shown) is actually better, aerodynamically, than the long thin cone in the subsonic region.

Since Mach 1 varies so much even on our own single planet, and Boltguns will be used on all kinds of different worlds, it'll likely be < 300 m/s to be defo subsonic most places where they have atmosphere.

For fast running fights, instinctively engaging targets from the hip at all ranges from muzzle to 1 km out, in wildly varying atmospheres and gravities, having a consistent hit point is more important than raw velocity for such a round. You want laser-like flatness of trajectory (though you will have to lead some targets a bit more, with the lower velocity).

Soooo, I'd have a consistent velocity (whilst the rocket is burning) of ~290 m/s (at standard sea level atmospheric conditions on Earth). The rocket isn't needing to provide 290 m/s per s acceleration, but merely counter the drag encountered at 290 m/s (so doesn't need anywhere near as much thrust) for a long ranged, consistent, gentle burn (making your propellant go that bit further, or/and needing less). Any unburned propellant remaining upon impact adds Incendiary to the other attributes, so it's certainly not wasted.

[Obviously it won't be exactly that simple (still need to get from muzzle velocity up to ~290 m/s etc) but this is just a friendly chat and not an epic patent application. ]