How many Spartan-IVs to take down an Ultramarine squad?

[Balrog]

Standard ten-man Ultramarines tactical squad, armed with bolters, frag grenades and combat knives. The sergeant is armed with a plasma pistol and chainsword, while two of the Space Marines trade their bolters in for a plasma gun and heavy bolter respectively. They are patrolling down a typical urban landscape when the fight occurs.

The Spartan-IVs are as of Halo 5 with the newer suits. The question is how many of them would you need given the following restrictions:
A)Just standard weaponry (pistol/SMG/battle rifle/assault rifle/DMR) and frag grenades.
B)Any weapon from multiplayer (limit six Req points per Spartan)
C)Any weapon or vehicle from multiplayer (limit eight Req points per Spartan)

[Q99]

It's *really* hard to drop SMs with standard weapons. Like, really really hard.

On the flip side, give 'em energy weapons and heavy weapons and they've got a shot. Still probably want multiple spartans per marine...

[Jub]

To answer this we ought to first look at a standard Ultramarine in terms of armor and firepower. I'm going to start with the firepower side of things because that tells us a fair bit about space marine toughness.

The standard bolter is a 4-round burst weapon that a .75 caliber (19mm) two stage gyrojet round with an explosive core. The round is tipped with a Diamantine spike that can penetrate many common types of armor. Behind that is a depleted uranium bullet that the Diamantine tip sits in and behind that that is the explosive core of the round. At the very rear is the propellant charge which gets the whole thing moving.

Speaking of moving, the first stage works like a normal gun, sending the round out of the barrel at 'significant velocity' and then the second stage kicks in accelerating the round to even higher speeds. Upon impact a time delayed fuse starts so that the round tries to detonate with its target, thus the bolter has two mechanisms for dealing damage.



1. A solid-fuel rocket propellant base
2. An outer casing containing conventional charge
3. Gyrostabiliser
4. Mass-reactive fuse. Has a split-second timer to delay detonation upon impact until after the shot penetrates the target.
5. Hardened diamantine penetrating tip. This allows for the bolt to penetrate most armour before detonation.
6. Main Charge
7. Depleted uranium core. This is a very dense material, adding weight and thus momentum to the round when in flight. This aids in the bolt's penetration of the victim.



Ignore, the 40mm round, it's not to scale and more to show that 40k bolter rounds are kind of stubby.

Also, I don't think any of these diagrams are official, and if anybody has official bolter round diagrams I'd be more than happy to scale from those.

With that disclaimer out of the way, I'll start scaling the kinetic energy of a bolter round based on these diagrams, the densities of the known materials (for the DU slug), and the density of diamond and gunpowder for the tip and explosive core. For speeds, I'm going to go from a fairly weak BB gun velocity of 500 ft/s, 690 ft/s from a 148 grain .38 special round from a 4" barrel, 715 m/s for a 7.62×39mm from an AK-47 1,230 ft/s from a Glock 17 firing a 9×19 mm Parabellum round, and finally 3110 ft/sec for a 5.56X45mm NATO fired from an M16. This should give us a good range of values to work with to provide an idea of the purely kinetic power of these rounds.



Scaling from this image.

Our round is 256 px long by 85 px wide from tip to base. This gives us a height of 57.37 mm and a diameter of 19.05 mm based on the known .75 caliber of this round. The DU slug is 104 px long and 70 px wide, the shape makes getting an exact volume tricky, but the main cutaway section in the bottom is 61 px long by 31 px wide. I'm going to treat the DU slug as a 104 px long by 70 px wide cylinder with a 61 x 31 cylinder missing from its base. This gives us a volume of 3989.8 mm3 for the DU slug. I rounded off to 4000 mm3 or 4 cm3 just to save myself some headaches. The density of DU is 19.05g/cm3 giving our DU slug a mass of 76.2 grams.

The diamantine tip is 45 px long by 37 px wide. It also has a funky shape but given that the rounds mass will be dominated by the DU slug I'm just treating it as a simple cone. This cone has a volume of 194.78 mm3 or 0.19 cm3 for a mass of 0.665 grams.

The explosive charge is 49 px long by 71 px wide measure from the main body of the charge for the length and the top of the main body for the width. I'm also treating this as a simple cylinder, again this isn't exact, but the DU slug is such a massive percentage of the mass that this won't skew the calculation much. This gives us a volume of 2.19 cm3 and, assuming a density of gunpowder, a mass of 0.25 grams.

I'm going to assume the rest of the round is void space because again that doesn't change our mass much. This gives us a total mass of 77.115 grams for our round. Plugging this into the equation for kinetic energy with our various speeds we get the following data:

500 ft/s = 895.53 J
690 ft/s = 1,705.44 J
715 ft/s = 1,831.26 J
1,230 ft/s = 5,419.37 J
3,110 ft/s = 34,646.52 J

If we compare this to the 7.62×51mm NATO round fired from a 24" barrel with an energy of 3,506 J, which should be comparable to the M118 7.62x51mm Full Metal Jacket Armor-Piercing used by the UNSC MA37 Assault rifle. So we see that the MA37 is ahead of the Bolter until we hit the 1000 ft/s mark, which makes sense because speed is a mush larger factor than mass when determining an object's KE. That said, I think that 1,000 ft/s probably makes more sense as a lower end for a bolter's muzzle velocity than the lower numbers just because I can't see a space marine wanting to risk hitting something at point blank range with less energy than a modern assault rifle round.

Now onto the 'fun' part of the calculation which is the explosive part of the bolter round. We don't know exactly how powerful 40k explosives are, but at the high end, they can fit the explosive force of a frag grenade into something the size of a coin. I'm going to scale off a British fifty pence coin as it's the largest coin in service at the time 40k was first being written as well as five and ten pence coins as lower and mid-sized coins respectively. As for the grenade we're basing this off of I'll be using the US M67 grenade with a filling of 0.4 lb (0.18 kg) of Composition B. Composition B has a density of 1.65 g/cm3 which means our grenade has a 109.09 cm3 of explosive inside of it.

Now most coins aren't simple cylinders, but I'm going to be lazy and assume that they are for our purposes. If anybody wants to do the extra work and get me more exact volumes I'd be happy to use them.

Fifty pence volume = π x 13.65 mm2 x 1.78 = 1041.92 mm3
Ten pence volume = π x 13.65 mm2 x 1.78 = 872.16 mm3
Five pence volume = π x 9 mm2 x 1.7 = 432.6 mm3
Average volume = 782.23 mm3

The 50p coin has a volume 104.7 times smaller than that of the grenade's filling while the other coins have even crazier energy densities than that. This means that our explosive core has the energy equivalent of between 2.1 and 5 M67 grenades. Even if we assume that each coin only has half its volume filled with explosive that still between 1 and 2.5 grenades worth of bang per round. That's not something a spartan is going to want to get hit with. The plasma weapons are stronger, possibly by orders of magnitude than the bolter which is already a threat to kill a spartan in a single burst.

That concludes the part on space marine firepower. I'll do a post on how that relates to their toughness sometime in the next couple of days.

If anybody has concerns about my calculations or more accurate numbers for me to use feel free to correct me, I'm just trying to get us a rough baseline to work with. I'd especially like it if Connor MacLeod were to drop by so we could use his numbers.

[bilateralrope]

One detail to consider is that the recoil on a Space Marine bolter is often described as having too much recoil for a normal human to handle. I remember seeing somewhere that the recoil is enough to break an unaugmented humans arm.

That should provide a lower limit on how much power is in the launching charge of a bolter round.

[NecronLord]

If anybody has concerns about my calculations or more accurate numbers for me to use feel free to correct me, I'm just trying to get us a rough baseline to work with. I'd especially like it if Connor MacLeod were to drop by so we could use his numbers.

Consider yourself corrected:

The coin-explosives of the Ian Watson & Bill King books were in those books more powerful than bolter shells, and in the FFG Rogue Trader line, they appear under the name micro-grenades, IE relics of the Dark Age of Technology, that are again more powerful than bolt shells.

The Imperium doesn't make bolt shells using the same technology as micro-grenades, because the Imperium doesn't understand what it's doing when it makes micro-grenades, it just uses ancient machines to make them, and prays while the micro-grenades pop out.

You can't infer bolter firepower from micro-grenades.

[Purple]

Thing is, even if we do the lowest end thing and assume they are using explosives no better than we have today a direct hit from a modern 20mm HE round is still going to kill a spartan dead. Especially if it happens when the round has already penetrated his skin and is lodged in between his innards.

[Q99]

Yea, Space Marines have rapid-fire armor piercing grenades as their standard sidearm. And armor that normally takes multiple hits from the same to take down.

Spartans have..... normal bullets. And armor that can be taken down by said bullets. So SM weapons will shred them.

So you need things like rocket launchers, Spartan Lasers, incineration cannons, to give Spartans firepower to do damage, but they're still quite outarmored.

[Elheru Aran]

Re the micro-grenades: Remember that they're 'micro'... to Space Marines. I'm not saying they're actually disks the size of our heads, but I would expect them to be around 1.5-2in diameter, if not 3in. Not literally 'coin-sized'.

[NecronLord]

They're micro to humans too, they're used in the Ian Watson books by arbites, and available to anyone with the throne gelt in Rogue Trader. They're not standard astartes equipment, except in books by the two abovenamed authors, either.

[Elheru Aran]

They're micro to humans too, they're used in the Ian Watson books by arbites, and available to anyone with the throne gelt in Rogue Trader. They're not standard astartes equipment, except in books by the two abovenamed authors, either.

Huh. OK, I haven't read those.

Sure they aren't just 2 different versions of same though? Given that bolters are in semi-common use by both standard humans and Astartes, it makes sense to have two sizes, which IIRC is more or less accepted... but I haven't debated 40K in some time, so who knows.

[NecronLord]

I wouldn't think so, they're honestly very very obscure, they only pop up when someone wants to wank explosives from them, but given that thier operation is beyond the Mechanicus' understanding it's not particularly relevant.

Being from the DAoT they are probably designed for standard human use.

[Elheru Aran]

Well then. I suppose that says something about the dexterity available to Space Marine gauntlets, being able to handle what are *really* miniature explosives (to them) with ease. Carry on, then...

[NecronLord]

Now that I'm home:

A wonder of ages past, and still produced in tiny quantities in certain remote corners of the Calixis Sector, microgrenades are tiny, marble-like devices that detonate almost as fiercely as full-size grenades. They are normally stored in a tube-like container that dispenses and primes a handful of grenades simultaneously, allowing them to be thrown immediately.

A number of microgrenades may be thrown at once, in a manner similar to firing a gun on semi-auto mode. When rolling to hit—with the normal bonus for firing on semi-automatic the number of successful hits caused by the weapon (determined by your degrees of success as normal) is the number of grenades that successfully hit their target. Any grenades thrown that do not hit in this manner scatter as normal, but all the grenades detonate whether they hit or not. Each dispenser contains 12 microgrenades, and the listed weight is for a single dispenser.

Doesn't actually say they're DAoT archeotech, just that they're a wonder of ages past by 800.M41, but they're still something different to the explosive in bolters.

[Black Admiral]

Platoon strength, at least. The S-IVs' weapons, armour, tactical systems and personal capabilities are all across the board inferior to Astartes gear and augments, and they themselves are frankly just not very good soldiers.

[Eternal_Freedom]

Platoon strength, at least. The S-IVs' weapons, armour, tactical systems and personal capabilities are all across the board inferior to Astartes gear and augments, and they themselves are frankly just not very good soldiers.

That last part is probably due to them being (IIRC, haven't played Halo 5) special forces rather than general combat troops. They're capable, sure, but in a different set of things to what regular infantry would be.

The Astartes are difficult enough to kill with 40K small arms, I cannot see them struggling very much against stuff that is to them M3 weaponry, not M41.

[Black Admiral]

Platoon strength, at least. The S-IVs' weapons, armour, tactical systems and personal capabilities are all across the board inferior to Astartes gear and augments, and they themselves are frankly just not very good soldiers.

That last part is probably due to them being (IIRC, haven't played Halo 5) special forces rather than general combat troops. They're capable, sure, but in a different set of things to what regular infantry would be.

Except, if that's the case, then they're even worse. Their support staff is non-existent, they don't plan, don't do any kind of prep work for their missions - more than once, they've only been briefed about what they're supposed to be doing on landing in the mission area - and trying to de-conflict their support requests or chop support to them from outside is a nightmare because of the dumbass way they're set up (even before touching on the multiple extremely blatant traitors in their ranks who still weren't caught before successfully murdering several of their colleagues).

Plus, they're prone to doing very dumb, and reckless, shit, as seen in Halo 5's intro with Fireteam Osiris deciding that the sensible thing to do is free dive through an ongoing aerial and ship-to-ship engagement (one can only imagine the expressions in their support ship's tactical centre if one were to get sideswiped by a Seraph or happen to pass through airspace too close to a pulse laser beam).

[Elheru Aran]

To be fair it's not like some Astartes aren't prone to "doing very dumb and reckless shit"... that said, Smurfs are a bit less likely to be prone to glory-hound crazy moves versus, say, Space Wolves or Flesh Tearers.

Spartan heavy weapons could probably put a dent in Astartes armour-- the vehicle railgun for one. If you throw Covenant weapons into the mix, with the plasma and all, that might be a little more interesting.

Being hit by bolter rounds-- heavy or otherwise-- isn't going to do the Spartans any good, though, and neither will getting close enough for physical combat, if any of them are fool enough to try and rifle-club the Space Marines.

This would just be murder if they went up against some of the more specialized Chapters like Iron Hands (archaeotech coolness), Raven Guard (frickin' ninjas) or Salamanders (burny death)...

[Purple]

To be fair it's not like some Astartes aren't prone to "doing very dumb and reckless shit"... that said, Smurfs are a bit less likely to be prone to glory-hound crazy moves versus, say, Space Wolves or Flesh Tearers.

The difference being that if fluff is to be believed the Astartes actually are overpowered enough compared to almost everything else that it's not really reckless and dumb. Charging a tank with nothing but a sword is not insane if your armor can take tank shells head on and your sword actually can cleave through armor (made up example, don't ask for a quote).

[Jub]

If anybody has concerns about my calculations or more accurate numbers for me to use feel free to correct me, I'm just trying to get us a rough baseline to work with. I'd especially like it if Connor MacLeod were to drop by so we could use his numbers.

Consider yourself corrected:

The coin-explosives of the Ian Watson & Bill King books were in those books more powerful than bolter shells, and in the FFG Rogue Trader line, they appear under the name micro-grenades, IE relics of the Dark Age of Technology, that are again more powerful than bolt shells.

The Imperium doesn't make bolt shells using the same technology as micro-grenades, because the Imperium doesn't understand what it's doing when it makes micro-grenades, it just uses ancient machines to make them, and prays while the micro-grenades pop out.

You can't infer bolter firepower from micro-grenades.

Thanks NL, I wasn't sure where the micro-grenades stood in terms of general use. I knew they were from older works and on the rare side, but not that they were DAoT level rare.

That being the case, and with bolt rounds being weaker, and probably by a fair bit, than a micro-grenade I'm going to adjust my numbers down by a factor of 8 on the upper end and 16 as a lower end. This leaves us with bolter rounds that are, on the low-end 1/16th of a grenade and at the high end equal to around 1/3 of a grenade. That's a fairly wide range, but it still tells us that the amount of bang in a bolter shell is nothing to sneeze at, especially when it's designed to burst under your armor.

I think it would be fair to say that a Spartan-IV is going to have serious issues taking a burst or two of bolter fire and staying in the fight.

I also realize that I messed up on my AK-47 muzzle velocity, it should be 2,350 ft/s not the 715 ft/s I listed. I accidently grabbed the numbers from the m/s column I was taking my data from. With those corrections out of the way let's take a look at another post about the bolter's killing power from Connor MacLeod.

This has been brewing at the back of my mind for some time now. I admit when I actually starrted doing the analysis bit I was at a complete loss as to how to quantify the explosive effects of the almighty bolter. The kinetic/imapct effects were simpler (Recoil, or by measuring the mass of the projectile and so on and so forth.) I knew some about that, but precisely zippo about high explosives.

It would be "roughly" possible to get an estimate by assuming a projectile mass and internal composition of explosive to get an estimate, but it would be just an estimate, rather than a measurement of effects. So no really accurate attempt at quantifying bolters was possible. Until Mythbusters at least.

A number of Mythbusters episodes have centered around the use of explosives ant the human body. Two notable ones involved grenades and one that involved exploding pens. With these, we've at last got quantiative evidencee to measure bolters by.

Generally speaking, I shouldn't have to describe the various examples of bolter effects - everyone is well acquainted with the effects of bolter shells on the body (I've documented many as ti is.) Some shells blow large fist or head sized holes in the body (human or space marine, depending on source) - which is roughly between 10-20 cm diameter holes. Others blow heads, torsos, or even entire bodies apart. Some vaporize or cauterize, but I won't address those here, as they're easily calced.

The first calc (and the easier) is the Grenade on a ballistics gel body (see link above.) It was a standard fragmentation grenade, and it managed to basically blow apart the torso. Knowing that, we simply need a hand grenade to go by. For convenience sake I'll use the US M61 and M67 Grenades. The former has 6.5 ounces of Composition B, and the latter has 5.5 ounces. We'll call it roughly between 156-185 grams of Composition B, which is roughly 1.35 times more powerful than TNT - or 5.7 MJ per kg. This yields between 900 and 1000 kilojoules of energy (though of course, energy is only patr of the effect ove a conventional explosive - the blast is the more damaging part.)

So, given that, and given we know some bolter shells can blow torsos apart, ,we can conjecture that a bolter round (or several - 3rd edition says that bolters will fire 3-4 shells per trigger pull) is roughly equal to a Grenade.

There are some considerations. Since its an omnidirectional blast, technically a grenade won't direct ALL its energy to the person - part of it will probably hit the ground and may reflect up, but its at least half. Also, its a fragmentation grenade, and not all bolter shells are frag (only the metla storm are.) REgular grenades would be more equal to a "concussion" grenade, and thus might not be as effective. Both situations are probably mitigated somewhat by internal detonation as well, though.

I should note that an earlier episode dealing with nitrogylcerine patches featured a similar case where a ballistics gel torso was obliterated by high explosives and nitro poured into a small (several inch diameter) cavity in the gel dummy's chest (the explosive, which remained unidentified, was by my estimates only a bit smaller then the hole.) and by my estimates provided similar results above.

Now, that one is quicker, but less precise. The "exploding pen" (see liknk above) is harder, but was done with multiple examples.

The first example used a "regular" sized pen. The Mythbusters measured its internal volume at around 3 cubic centimeters. It also put a "grapefruit" sized hole in the target (which is roughly fist or head shaped)

We don't hear the type fo explosive used, but we can guess.

TNT has a density of 1.654 g/cm^3, and obviously a RE of 1.0 (since its the baseline.)

RDX has a density of 1.82 g/cm^3 and a RE of 1.6.

The (currently) most powerful explosive I am aware of is octanitrocubane:

it has a RE of 2.7 and a density of 2 g/cm^3.

By regular TNT, the pen would carry around 5 grams of TNT, 5.4 grams of RDX, or 6 grams of ONC. The energy equivalents would be 21 kilojoules for TNT, 36.2 kilojoules for RDX, and 68 kilojoules for ONC.

For the most parrt I'm betting it was something better than TNT (it sounded like it might be restricted or secret) so ti would probably be between RDX and ONC in terms of power.

The second one was actually easier to measure. Jamie said that it had the "better part" of as tick of dynamite in it. "Better part" which argues more than half (backup definition here.)

A stick of dynamite is about 2000 BTU, which is confirmed here. Dynamite is also noted to have around 5000 BTU per pound here, and an average (20 cm long, 2.5 cm diameter) stick is probably around 200 grams, so it works out. Half of that, would be around 1000 BTU, or a little over one megajoule (at least.)

So, we can say between 1-2 megajoules to blow up a torso with the exploding pen, although again its an omnidirectional blast which will affect things (though by no more than half.).

Its also interesting to note that yield-wise, it was said that the other pen (with the unknown explosive) had 1/6 the yield of the second test, suggesting it was closer to 100-200 kilojoules of TNT to blow a fist/head sized hole in the target.

Note that while the Mythbusters weren't "convinced" by this blast, it probably would match what is described in 40K sources for bolters blasting torsos.

The last pen explosion isn't quantified, but was considerably bigger than the second or first one, and it also totally obliterated the torso. Going by estimates, I'd say its at least 50% longer and perhaps twice the diameter of ths second pen, so again its probably 6x larger. This would suggest that it was explosively comparable to 1-2 kg of TNT.

I would not generally consider the last one as being analogous to bolter ounds as the blast effects observed in the video seem to encompass a substantially greater volume than the earlier two detonations, and bolters aren't quite THAT nasty (IE they're not area affect wepaons like grenade or missile launchers.) so we can probably rule that one out.

Taking all of the above into context, its fair to say that bolter shells are probably equal to many tens or hundreds of grams of TNT, given comparison of observed effects.

-------------

Oh, as an addendum:

I mentioned erlier that before this the best means of estimating Bolter firepower was to gauge the internal volume of the shell.

We know bolter shells are about .75 calibre, so they are roughly 1.9 cm in diameter. The length of the shell appears to be roughly 3-4x the diameter as well, which would be around 5.7 and 7.6 cm. Judging by the cutaways of bolter shells, I'd esitmate no more than half - more probably a third, of the internal volume is dedicated to explosive (the rest is propellant and casing.) The total volume of the shell would be roughly between 17 and 23 cubic cm by estimate, so the internal volume of the explosive is probably between 8-12 cubic centimeters (for half) and 6-8 cubic centimeters (for a third)

With the densities/REFs outlined above, we can figure on the shell containing some 10-25 grams of explosive. (Which would roughly make sense given the shells probably mass between 50-100 grams, or about the size/mass of 12.7-20mm shell in real life.)

by real life explosive, this comes out to between 40 and 100 kilojoule for TNT, up to 113-283 kilojoules for ONC. Given other eamples of explosives (basilisk shells, grenades, etc.) its quite likely that 40K explosives are at least as powerful as ONC, if not more powerful (many times more powerful than TNT, in other words.) Its quite possible 40K explosives are 5 or even 10x more powerful (especialyl going by grenade and basilisk references), which the "effects based analysis" above would concur with, as the increase would yield outputs more consistent with a grenade (hundreds of kilojoules)

A heavy bolter, incidentally, IIRC, is roughly twice the size/mass of a regular bolter shell, so it probably also has at least twice the explosive effect.

Taken from this thread.

Looking at his numbers next to my revised numbers they roughly agree on the explosive oomph in a bolter round. With my numbers giving 11.5g and 60g of explosives and his being tens to hundreds of grams of TNT. Given these calculations, I'm going to work with 10 g, 50 g, 100 g, 250 g, and 500 g of explosive per shell for our explosive energy. This is easily done as, by convention 1g of TNT produces 4184 J of energy. Thus, we get the following in terms of bolter energy values.



As we can see we're looking at a large range depending on assumed velocity and explosive, but even at the lowest end we're looking at 45.4 KJ of energy for a bolter round versus 3.5 - 5 KJ for standard Spartan-IV small arms and even if we gave them something like an M2 Browning as a small arm that's 18-20 KJ of energy, less than half of our lower end bolter round and an insignificant fraction of the highest end calculation.

Now that we have our numbers for firepower we can start looking at just how tough space marine armor is.

Both in fluff and on the table top a standard space marine bolter doesn't defeat their own armor very easily. It generally takes a large volume of bolter fire before a section of armor is defeated, that or a rather lucky hit to a weak point. Even that isn't the end, as the space marine beneath the suit is vastly tougher than a baseline human. This is due to a number of implants that do things like fuse their ribs into a bullet resistant plate over their organs, allow them to form scars the way we form scabs, a second heart, an extra lung, and the black carapace which links them to their power armor.

Another way to look at them is to treat them as a walking APC with between STANAG Level 5 and 6 protection. Needless to say, a Spartan-IV is probably going to want their heaviest weaponry if they're going to tangle with a space marine.

[Simon_Jester]

If anybody has concerns about my calculations or more accurate numbers for me to use feel free to correct me, I'm just trying to get us a rough baseline to work with. I'd especially like it if Connor MacLeod were to drop by so we could use his numbers.

Consider yourself corrected:

The coin-explosives of the Ian Watson & Bill King books were in those books more powerful than bolter shells, and in the FFG Rogue Trader line, they appear under the name micro-grenades, IE relics of the Dark Age of Technology, that are again more powerful than bolt shells.

The Imperium doesn't make bolt shells using the same technology as micro-grenades, because the Imperium doesn't understand what it's doing when it makes micro-grenades, it just uses ancient machines to make them, and prays while the micro-grenades pop out.

You can't infer bolter firepower from micro-grenades.

The catch is that they don't understand what they're doing when they make bolter rounds either. The real question is whether the people who built the machines to make the ammunition, millenia in the past, used similar explosives for each weapon.

One thing is clear: given that heavy bolters are a common type of ammunition throughout the Imperium for vehicle and infantry heavy weapons, it seems likely that bolter ammunition is in truly enormous production. Space Marines probably use the most powerful types available, which are likely to be the ones that were designed to be made with high-end explosives back in the day.

[Black Admiral]

To be fair it's not like some Astartes aren't prone to "doing very dumb and reckless shit"... that said, Smurfs are a bit less likely to be prone to glory-hound crazy moves versus, say, Space Wolves or Flesh Tearers.

However, Astartes are, mostly, not special forces as is in common usage, they're shock assault troops, which requires a different mindset (although, certainly, the Vlka Fenryka take it rather far at times, and the Blood Claws take it to an extreme even by that standard (although that's part of the point, letting them work out their youthful stupidity early in service - and at least they can't make bets that're permanently binding any more)). The Flesh Tearers are a bit of a special case, with the way that the Black Rage affects them.

On the other hand, the Deathwatch - who do perform a lot of what we'd see as special forces tasks - are notably more cautious, and meticulous planners (even if their plans have built into them the expectation that at some point, the mission will go straight to hell, in a fancy paper hat, and then it's weapons-free time).

[Q99]

Space Marines vary a lot in temperament. Salamanders are known as being cautious, Iron Fists love fortifications (both using them and taking them down), Raven Guard use speed but very tactically in hit-and-run manners, and Ultramarines aim to be jacks-of-all-trade. Still, I would say on the whole their abilities and fanaticism lend themselves to aggressiveness. The armor and all the redundant organs means taking some hits to get the job done often works.

[NecronLord]

The difference being that if fluff is to be believed the Astartes actually are overpowered enough compared to almost everything else that it's not really reckless and dumb. Charging a tank with nothing but a sword is not insane if your armor can take tank shells head on and your sword actually can cleave through armor (made up example, don't ask for a quote).

Can we get away from this idea that they're overpowered? It seems to come from the asinine idea people have that the tabletop game poorly represents marines; this isn't so. It's not exactly linear, in that a marine is more resilient to lasgun fire than they are in TT, but anything on the tabletop that can kill them can usually kill them in the same manner in lore; for instance a no-name marine who's not a captain or great hero fighting a tyranid warrior in hand to hand combat is dead meat.

The basic marine, as opposed to the mighty chapter champion, is well represented by the boardgame, and isn't that overpowered compared to other things in universe, for instance take a look at the Triarch Praetorian in the World Engine novel that kills marine soldiers in single slaps of his hands, and concusses a chapter master with a punch and sends him flying across the room, then kills that same chapter master with ease.

There are many, many, manymanymany things in universe that break marines.

The catch is that they don't understand what they're doing when they make bolter rounds either. The real question is whether the people who built the machines to make the ammunition, millenia in the past, used similar explosives for each weapon.

One thing is clear: given that heavy bolters are a common type of ammunition throughout the Imperium for vehicle and infantry heavy weapons, it seems likely that bolter ammunition is in truly enormous production. Space Marines probably use the most powerful types available, which are likely to be the ones that were designed to be made with high-end explosives back in the day.

It's not a catch at all; as I said earlier, even in the books microgrenades appear in, they are more powerful than bolter shells. Ragnar blackmane uses them as a modern/WW2 soldier would use grenades; to destroy things that his rifle cannot. In Rogue Trader they have outright more damage. In some old fluff, grenade launchers, the things you trade your boltgun for, when you want something with more boom, fired microgrenades. Nowhere is the idea that a space marine bolt shell has the same energy density as a microgrenade supported by evidence.

[Simon_Jester]

Sorry. My original counterpoint was aimed at the "the Imperium doesn't know how microgrenade explosive is made and can't be duplicating it in bolter shells." I don't think that specific point is applicable, because they don't know how bolter rounds are made either, and could be either using or not using microgrenade explosive in bolters, depending on whether the ancients who built the machines to make the ammo decided to use it that way.

But...

It was kind of pointless for me to bring this up since you were right about the "microgrenades explode more forcefully than bolter shells, even if the bolter has a physically larger explosive charge" point.

[Purple]

There are many, many, manymanymany things in universe that break marines.

And yet there are also manymanymany more things that break everyone but marines. And thus there are a lot of things that marines do that look insane to us from our perspective because we'd get broken doing them but not to them. Like for example charging at a machine gun nest (not heavy bolter, but just regular machine gun equivalents) to try and melee the crew, rushing an APC to try and rip it apart, going into melee with orks etc.

This said, the whole energy calculation on bolter shells is approaching the problem from the wrong angle. You can't just add the kinetic energy of the shell up with the explosive power of the filler and get any meaningful result as to evaluating the terminal effects. You people are adding up apples and oranges.

What you need to do is establish if the kinetic energy alone is sufficient when combined with the material properties of the shell to ensure penetration. If yes, figure out how much if any harm the residual energy would cause to the body and than separately figure out how the explosive content would effect it. Because remember, two different effects need separate evaluation. If no, than figure out what the effect of the explosive will be on external application as well as what effects the spartan will feel from being slammed hard by the projectile even if it does not penetrate.