(RAR) Unnamed Ultramarine VS M1A1 Abrams (40K + Real Life)

[Batman]

The tank is using sabot rounds as per the OP. No blast radius.

[Ziggy Stardust]

Zigzagging doesn't work to begin with, it will definitely won't work against a gun that fires something that actually has a blast radius. The only thing it does is lengthen the path the Space Marine would have to take to get to the tank, unless the Space Marine could actually dodge the bullets.

To be fair, though, that article doesn't actually say that running in a zig-zag pattern doesn't work at all, but rather that the choice of whether to sprint in a straight line towards cover or run in a zig-zag pattern towards that cover is something that should be decided on a case-to-case basis, rather than saying either method is inherently superior. The author even mentions that he, personally, would run in a zig-zag pattern. I'm not saying the Marine should necessarily zig-zag, mind you (with the high speeds a Marine is capable of running at full sprint, it's probably smarter for it to try and close the distance as quickly as possible, unless cover is available). I just want to do justice to the full context of that article.

(EDIT: I would also note that the informal study conducted by that article is really only applicable to one specific tactical situation, and likely isn't generalizable without larger, more controlled studies to back it up)

[Sea Skimmer]

You guys know the M1 tank has a canister round right? If the tank only has sabots then the Marine must have no weapons at all.

[U.P. Cinnabar]

Autocannon really depend on the writer to some degree. Heresy era, they were decent anti-armour weapons as they had better shells back then... or something like that... tougher too as you could use them as close-combat weapons (obviously we're talking Marines here, your usual scrub Guardie isn't going to be waving one around).

Oh, almost forgot multilasers. CS Goto (may his name go into the pits of Tzeentch) decided they were the be-all and end-all of Marine heavy weaponry for some reason... anyway functionally they're largely equivalent to autocannons from what I recall except obviously you don't have to reload them. Not as good against armour or something.

Multi-lasers, or at least the Rapier multi-laser, were not as good against armor as they were against air and infantry targets, no.

[Rogue 9]

Autocannon really depend on the writer to some degree. Heresy era, they were decent anti-armour weapons as they had better shells back then... or something like that... tougher too as you could use them as close-combat weapons (obviously we're talking Marines here, your usual scrub Guardie isn't going to be waving one around).

Oh, almost forgot multilasers. CS Goto (may his name go into the pits of Tzeentch) decided they were the be-all and end-all of Marine heavy weaponry for some reason... anyway functionally they're largely equivalent to autocannons from what I recall except obviously you don't have to reload them. Not as good against armour or something.

On the tabletop at least, a multilaser is significantly less penetrative than an autocannon (a multilaser, for instance, has no chance of penetrating the front armor of a Chimera, while an autocannon definitely can, and the autocannon has a much higher armor penetration value against infantry targets). Also, multilasers aren't used by Marines, and as I recall Marines don't use infantry autocannons in M41 either. (Chaos does, but that's a different animal entirely.)

[Elheru Aran]

Also, multilasers aren't used by Marines

Goto begs to differ :V

(Chaos does, but that's a different animal entirely.)

Yeah, occasionally literally in some cases... That said, I'm not sure there's any real mechanical reason why Loyalist Marines couldn't, it's strictly a matter of flavor. In-universe it's because they found assault cannons and decided they preferred rate of fire to firepower. Pretty sure the Horus Heresy line of Marines, both Loyalist and Traitor can use autocannons.

[Adam Reynolds]

You guys know the M1 tank has a canister round right? If the tank only has sabots then the Marine must have no weapons at all.

What a surprise. Yet another case of a fanboy massively underestimating real technology.

Though it is possible the armor level would withstand something like that. How tough is ultramarine armor?

To be fair, though, that article doesn't actually say that running in a zig-zag pattern doesn't work at all, but rather that the choice of whether to sprint in a straight line towards cover or run in a zig-zag pattern towards that cover is something that should be decided on a case-to-case basis, rather than saying either method is inherently superior. The author even mentions that he, personally, would run in a zig-zag pattern. I'm not saying the Marine should necessarily zig-zag, mind you (with the high speeds a Marine is capable of running at full sprint, it's probably smarter for it to try and close the distance as quickly as possible, unless cover is available). I just want to do justice to the full context of that article.

I suspect much of the logic about running in a straight line being better comes down to the fact that people will likely overcorrect and zig zag too much while under stress, which increases the time they are exposed to fire while running for cover. Which was an excellent joke from Generation Kill:


Another factor is that they were dodging simmunition rather than bullets in that test, which are both less accurate and travel slower. Both of those factors would make dodging artificially more effective than in combat conditions. There is also the factor that in most real situations there is more than one target, which again makes getting out of the line of sight more valuable than being slightly harder to hit.

[Sea Skimmer]

What a surprise. Yet another case of a fanboy massively underestimating real technology.

Though it is possible the armor level would withstand something like that. How tough is ultramarine armor?

I'd expect his main armor would, that's not actually that demanding except utter point blank, being round balls they slow down fast. However his equipment and sensors? Doubtful. But then that's another problem at hand, sure the chest plate might withstand all kinds of things, even with modern materials the 40K marines are implied to weigh enough that we might be able to armor the chest against a lot of things. However what about the head, and say, the fingers? What can those withstand? Do they have any biological material left inside of them or are they semi solid? Basic problem with typical simplistic power armor 'immunity' theory that is generally ignored. Even in universe it would make no sense for the armor on a Marine to be equal everywhere. The guys are super cyborgs, so even having an arm torn off should have a good survival chance. You would intentionally want to stack armor on the chest and head.

Now in a large scale battle limb vulnerability like that can just be accepted in a proportional basis, but when people start insisting that even thousands of rounds of concentrated fire (M1 coax belt box holds linked 2,800 rounds on its own) mean nothing, well, this requires arbitrary video game hit point logic. Real things won't ever work like that.

Then you've also got the momentum factor in play, even a being with immunity can still be knocked over, and being knocked over by a 120mm scaled round, or probably even the sabot pedals, which have been known to cut down small trees, becomes a very serious problem. Also muzzle blast. Might not be fatal, but how does the Marine keep the soot off his visor?

[U.P. Cinnabar]

Autocannon really depend on the writer to some degree. Heresy era, they were decent anti-armour weapons as they had better shells back then... or something like that... tougher too as you could use them as close-combat weapons (obviously we're talking Marines here, your usual scrub Guardie isn't going to be waving one around).

Oh, almost forgot multilasers. CS Goto (may his name go into the pits of Tzeentch) decided they were the be-all and end-all of Marine heavy weaponry for some reason... anyway functionally they're largely equivalent to autocannons from what I recall except obviously you don't have to reload them. Not as good against armour or something.

On the tabletop at least, a multilaser is significantly less penetrative than an autocannon (a multilaser, for instance, has no chance of penetrating the front armor of a Chimera, while an autocannon definitely can, and the autocannon has a much higher armor penetration value against infantry targets). Also, multilasers aren't used by Marines, and as I recall Marines don't use infantry autocannons in M41 either. (Chaos does, but that's a different animal entirely.)

During the Horus Heresy, the Astartes did use both multi-lasers and autocannon; however, both of these weapons systems became exclusive to the Imperial Guard.

[Elheru Aran]

What a surprise. Yet another case of a fanboy massively underestimating real technology.

Though it is possible the armor level would withstand something like that. How tough is ultramarine armor?

I'd expect his main armor would, that's not actually that demanding except utter point blank, being round balls they slow down fast. However his equipment and sensors? Doubtful. But then that's another problem at hand, sure the chest plate might withstand all kinds of things, even with modern materials the 40K marines are implied to weigh enough that we might be able to armor the chest against a lot of things. However what about the head, and say, the fingers? What can those withstand? Do they have any biological material left inside of them or are they semi solid? Basic problem with typical simplistic power armor 'immunity' theory that is generally ignored. Even in universe it would make no sense for the armor on a Marine to be equal everywhere. The guys are super cyborgs, so even having an arm torn off should have a good survival chance. You would intentionally want to stack armor on the chest and head.

This is pretty much how it goes in 40K. Terminator armour is an extreme case of this 'stacking'. As for actual toughness... *sigh* depends on what you read. We have the classic case of a bare-headed Space Wolf in Terminator armour being stepped on by a Warhound Titan and digging himself out with a minimum of injury. Standard armour will vary quite a bit, and then you can add in modifiers such as a rosarius, Iron Halo, artificier armour, master-crafting... etc.

Might not be fatal, but how does the Marine keep the soot off his visor?

Miniature windshield wipers. Or one of those electronic wiper things like they have in Halo.

(Seriously I don't know, there's hardly any mention of steam or smoke in 40K though apart from fires or flamethrowers so I assume they've managed to minimize such to a greater extent than we have)

I would say they can probably take blast fairly well though is my guess but I don't have any references on hand. The armour can be hardened against vacuum and against biological or chemical hazards, but those are different mechanisms than blast overpressure...

[Simon_Jester]

Marine armor on the tabletop offers almost no protection against large-caliber exploding shells of the sort that use blast as a primary kill mechanism. At the same time, they are canonically fully enclosed 'hard' suits, so it's hard to say.

I'd expect Marine armor to fail in significant ways if you hit it with hundreds of .50 caliber rounds, and equipment damage would start racking up as a major problem somewhere in the double-digits number of hits. This is one reason I figured on the whole issue hinging on relative levels of intent to kill. If the Marine realizes he has no cover and starts sprinting toward the tank right away while the tank takes significant time (e.g. 20-30 seconds) to realize he's out there and aim a gun at him, then he has a decent chance. If the Marine is standing still and getting his bearings while the Abrams points its weapons at him, he's screwed, because the main gun could practically put a round through his left nostril at that point. And even if that somehow misses, a deluge of .50 caliber fire will probably land enough hits to be a major problem for the Marine in the few dozen seconds it takes him to close.

Thinking about protection levels, and given that we are dealing with futuristic materials here, I suspect that Marine armor will provide something like protection nigh-immune to .50 caliber level threats over just about every "large plate" part of the body, including the plates on the arms and legs. If it didn't, then virtually all veteran Space Marines would have had their arms and legs shot off by attrition a long time ago. That is not the case; Marines with cybernetic limbs tend to be a minority.

It may not be feasible for them to provide that level of protection on the fingers, although (and for that matter because) shooting an individual finger off a Space Marine probably won't stop them. And I'm pretty sure Space Marine armored gauntlets do provide articulated protection for the fingers, not just sticking the fingers into the 'palm' of a big motorized gauntlet- though at the same time, I'm quite sure that things like powerfists and Terminator armor DO work on those principles.

[Rogue 9]

Marine armor on the tabletop offers almost no protection against large-caliber exploding shells of the sort that use blast as a primary kill mechanism. At the same time, they are canonically fully enclosed 'hard' suits, so it's hard to say.

Not completely true. As a primary Guard player, I can attest that there are a great deal of blast weapons in the game that power armor laughs at, to include basically all of them except battle cannons, Demolisher cannons, and Earthshaker artillery. And not just the lighter guns either; their armor also laughs at Manticore multiple rocket launchers, which have the highest Strength in the game bar Destroyer weapons. I'm not arguing that we should measure versus matchups by game mechanics, but it does offer a measure of what sorts of things the designers intend to easily penetrate power armor and what sorts of things they don't.

(For those unfamiliar, the tabletop game has two measures of weapon effectiveness; Strength, which affects chance to wound or penetrate relative to the target's Toughness or Armor Value for not-vehicles and vehicles respectively, and Armor Penetration, which is simply a value that defines what types of infantry armor the gun gets to ignore and, if low enough, improves the chance that a vehicle penetrated by it will suffer major systems damage. If the AP is not 3 or lower, Marines get to laugh at it unless it comes in sufficient quantity that they become statistically likely to fail at least one save. A Destroyer weapon, which I referenced above, is Titan and/or starship-grade weaponry, and bypasses all this by just killing everything.)

[Simon_Jester]

Well, basically, when I talked about large caliber exploding shells I was thinking of battle cannons (the howitzer-type guns found on typical Imperial Guard tanks), Earthshakers (the typical Guard support artillery, routinely used in either a self-propelled or towed platform), and Demolishers (a short range support gun mounted on assault guns and such).

The effect of such weapons is that, at least on the tabletop, their killing radius against fully armored Space Marines is equal to the killing radius against, say, Imperial Guardsmen who wear only light ballistic armor, or orks who generally don't even put a damn shirt on. This isn't especially realistic, but there it is.

The way I figure it...

Smaller caliber exploding shells (i.e. bombs from conveniently portable infantry mortars) and so on tend to rely more on fragmentation and less on blast. I'd figure that AP 4 artillery typically relies on fragmentation more than blast, while AP 3 artillery typically has enough raw explosive force in the shell for blast overpressure to be a major threat. Fragmentation is simply not a reliable way to kill Space Marines, which is understandable, since their armor would be pointless if it were not adequate to stop a supersoldier who took decades to train from being killed by random shrapnel.

However, I posit that the reason large-caliber artillery is much more effective against them than light fragmentation weapons is precisely because their armor does only so much good against blast. Then again, the armor does contain self-contained breathing apparatus and is hard to crush, so I'm not sure that's true. Plus this is all tabletop rules, so really all it does is prove/indicate that a large caliber artillery round can kill a Marine on a 'miss.'

[Rogue 9]

Yes, that's what I was getting at in a slightly more roundabout way. Stormshard mortars carried by Wyvern mortar carriers are described as fragmentation-based and the Storm Eagle rockets carried by Manticores contain cluster bomb warheads, while the high caliber guns we both mentioned are conventional large caliber, high explosive ordnance. The only fly in the ointment, at least in the Guard arsenal, is the Eradicator cannon, which is described as producing a heavy shockwave (justifying the fact that it Ignores Cover), yet despite explicitly working through overpressure is only AP4 and thus Marines don't care about it.

Still. The scenario describes the tank as armed with sabot rounds, and the 40k-equivalent Vanquisher rounds can punch right through Terminator armor. I'm fairly certain a direct hit from a modern main battle tank's cannon firing anti-tank rounds would mess up a power armored Marine really well.

[Sea Skimmer]

On fragmentation....you guys really think its one thing? In real life fragmentation is never all one uniform size even out of a single projectile. That being 'true' would make no physical sense except perhaps in a round ball with no preforations and some kind of super idealized grain structure. Conical shells and mortar rounds certainly do not explode with perfectly uniform effects, nor should they, and realistically any projectile that detonates (explodes is different) will need a fuse well, which means its got an asymmetrical shape.

The idea that fragmentation cannot kill space marines because they would be pointless if it could is downright laughable. Are space marines also immune to land mines? All modern armored vehicles are vulnerable to 152mm fragmentation to one degree or another, somehow they continue to be tactically useful even though they cost millions of dollars and require highly trained crews and vast logistical pipelines just to exist on the battlefield?

The only way you will get something like really uniform scaled fragmentation is if the casing of both is of similar COFRAM type with internal scoring, and that's never been popular with larger caliber artillery precisely because it devalues the rounds against material targets, and even just against foliage over distances. Pretty common in late cold war grenades and cluster bombs though, they would make few fragments otherwise. These days when people give a damn they've typically begun using embedded shrapnel balls instead, as that's much more reliable and uniform then COFRAM ever can be. You can only cut up the casing so much before it would fall apart upon firing.

For some actual numbers, in the case of a 120mm mortar round from 1952 the most common size bracket of fragment produced that they bothered to count (below 1/8th gram was not counted and weighed 461 grams) was 5/8th to 1.25 grams with 472 pieces, but the total weight was only 392 grams. In contrast in the 20-40 gram range they found 79 pieces but the total mass was 2097 grams. And the heaviest body fragment was 80 grams, but in the 40-80 range were only 7 pieces, total weight 315 grams. But meanwhile the entire tail fin assembly was blown off as one piece (this is normal for mortar ammo) and weighed 1131 grams. Shitloads of rounds were studied, blown up in enclosed tanks for ensure collection, results similar but never the same.

Meanwhile they also tested 12in HC battleship rounds among other thing, and to save time so I can go to bed, it produced lots and lots of fragments similar to the mortar rounds, and 155mm rounds for that matter, but it also produced hundreds of fragments in the 80-640 gram range. Which you know, 640 gram fragment at say 700m/s as it might be traveling a distance from the point of burst is about 144kj, similar to the muzzle energy of a 30mm cannon round. This was important BTW as to why bigger naval guns won out. Not just more accurate at long range, they simply did far greater damage on impact because heavy fragments like that could tear through heavy shipboard equipment, like say a gun mount or a engine casing, that could shrug off smaller fragments.

Shape matters. Bursting charge matters, more and stronger (which is a matter of several properties) will produce finer fragments. Case hardness matters, harder makes smaller fragments, but they might penetrate some material better. In fact its very important to match the burster to the shell case material to avoid making a poor range of fragmentation, unless the goal is actually to make a low collateral damage warhead in which producing a dust like fragmentation pattern is actually the goal. For bonus it matters if and how the shell is tamped against the ground too, this can as much as double the velocity of some of the fragmentation. And of course the shell's original velocity still applies, just because it explodes doesn't mean its original forward momentum vanishes.

These factors all work together, and can mean interesting things such as a 120mm mortar round with ~half the weight of a 155mm shell can actually be more engineered to be effective against personal in the open then a general purpose 155 round, because it produced a finer and more uniform hail of fragments suited to killing people. But it won't do nearly as well against troops hiding under so much as thick bushes or damage armored vehicles easily. And it can't physically survive preforating some items without breaking up that the 155 round would, with the right fuse, be able to fully penetrate before bursting like a commercial concrete roof slab.

On the other end of things, in the world wars the Germans designed shells for heavy guns that deliberately had small explosive burster charges and made few fragments. Seems less effective? Well this was because in the counter battery role killing enemy gun crews accomplished relatively little, because as long as as few enemy gunners lived they would simply go steal riflemen from the infantry and get the guns firing again soon after. And being made of hardened steels the guns themselves simply shrugged off small fragments from not so hardened shell steels. But one big fragment could permanently wreck the gun if it hit the right place, and that was what counted strategically. So they made the shells produce as many big fragments as possible, and screw the rest.

[Archinist]

Why is everyne using game mecahnics and talertrop rules as canon calcs? Those rulesets are used to make the game fair and balanced for al factions, and are very different from the book calcs. I mean, doesn't the tabletop say that a fully armoured space marine will only lift about 80kg, while a normal man will lift 60kg? Might not have been kilograms, but something definitely isn wrong there.

[NecronLord]

No, Archinist, the tabletop game does not say that.

[NecronLord]

Might not be fatal, but how does the Marine keep the soot off his visor?

He ends up taking it off, of course.

Yeaah.

[Zixinus]

Why is everyne using game mecahnics and talertrop rules as canon calcs? Those rulesets are used to make the game fair and balanced for al factions, and are very different from the book calcs.

Yes, but they are an indication just how powerful the weapons and armor are, which can be paired with observations of in-universe examples (lasguns can blast trough x feet of concrete, I think that was in a Ciaphas Cain novel somewhere). We know how much force is required to say, vaporize concrete. So we can work calculations from there.

It's actually how SDN works, there is tons of this on the main site and was heavily used when people argue about Star Trek versus Star Wars.

[Simon_Jester]

On fragmentation....you guys really think its one thing? In real life fragmentation is never all one uniform size even out of a single projectile. That being 'true' would make no physical sense except perhaps in a round ball with no preforations and some kind of super idealized grain structure. Conical shells and mortar rounds certainly do not explode with perfectly uniform effects, nor should they, and realistically any projectile that detonates (explodes is different) will need a fuse well, which means its got an asymmetrical shape.

Hell, even at the low resolution of the tabletop, what people said about Marine armor being "immune" to AP 4 weapons isn't actually true; said AP 4 weapons have a 33% chance of hurting the target on each shot.

I should have made a more precise statement, and I apologize for pushing your buttons with the one I made. Yes I am aware that shell fragments vary drastically in size and lethality.

Now, what I said was: "Fragmentation is simply not a reliable way to kill Space Marines, which is understandable, since their armor would be pointless if it were not adequate to stop a supersoldier who took decades to train from being killed by random shrapnel."

What I am trying to communicate is that shell fragments (like small arms fire) are such a common battlefield threat that armor which doesn't mostly protect against it is inadequate for the purpose Marine armor is intended to serve. The purpose of Marine armor is to keep supersoldiers alive to continue doing their jobs for centuries, despite seeing high-intensity combat on a regular basis. It doesn't have to provide a 100% certain guarantee that literally no shrapnel fragment including the base of a large caliber shell spinning through the air could ever hurt the Marine. But it does have to mean that most shrapnel from most fragmentation weapons bounces off. Especially the kind of fragmentation weapons typically employed against troops in the open (i.e. small fragments with limited penetration power).

Most of the things you can reliably kill a Space Marine with on the tabletop are in fact antitank weapons, and function rather well as antitank weapons. If you're Imperial Guard and you want to shoot down some guys in Marine armor? Fire a volley of antitank missiles at them. Open up with heavy energy weapons- the Guard has at least three different kinds of man-portable beam weapons, all of which have even better penetration than their missiles do. All those antitank weapons will cut through Marine armor like it wasn't there. They're also the same weapons that the same Guard formation would use to engage main battle tanks.

The Guard's machine guns, antipersonnel lasers, automatic grenade launchers, and light mortars aren't going to do much, though. All those weapons will inflict some casualties, but not a lot, because the armor provides reasonably effective protection against the weapons.

It would help to explain the high effectiveness of Guard heavy artillery against Marines (and comparably armored enemy personnel) if the Guard's shells are explicitly designed for large shell fragments. Though they're also just plain big shells, which I imagine helps.

The idea that fragmentation cannot kill space marines because they would be pointless if it could is downright laughable. Are space marines also immune to land mines?

Nope. Except the ones who fly or teleport over the minefield, of course. And yes, I know that anti-air mines are a thing, but I'm not sure anyone who designs 40k products knows that yet.

[Elheru Aran]

The idea that fragmentation cannot kill space marines because they would be pointless if it could is downright laughable. Are space marines also immune to land mines?

Nope. Except the ones who fly or teleport over the minefield, of course. And yes, I know that anti-air mines are a thing, but I'm not sure anyone who designs 40k products knows that yet.

With the caveat that for a land mine to kill a Space Marine, one would naturally expect it to be somewhat stronger than your typical anti-personnel mine for taking out your Mk 1 Traitor Guardsman. An anti-tank mine, for example, could probably do the job. This lines up with the idea that you use anti-armour weapons against Space Marines, of course.

And I don't think anybody is denying that a sufficient volume of anti-infantry fire could take down Space Marines. The problem is, of course, that the Marine knows it too. There's a cartoon that makes the rounds every now and then which has a Marine laughing off a lasgun blast, and then a few hundred extra lasguns show up and the Marine's not laughing anymore...

[Rogue 9]

On fragmentation....you guys really think its one thing? In real life fragmentation is never all one uniform size even out of a single projectile.

This is true. I apologize for incompleteness. The latest Imperial Guard codex actually gives fairly thorough descriptions of how the various warheads are supposed to work.

The stormshard mortar is a heavy, vehicle-carried weapon. Its shells are filled with inch-long sharpened steel flechettes, and are designed to airburst above the target to reach dug-in light infantry. The only way it kills Marines is through saturation fire or luck; fortunately for Guard players using one, the Wyvern mortar carrier they're mounted on carries four of the damn things. So we know from this that clouds of flechettes of this type don't easily penetrate power armor (though if they get through the armor, they will reliably kill a Space Marine).

Storm Eagle rockets are heavy ground-launched missiles that carry powerful, cluster bomb-like high explosive warheads. Said warheads can do a number on most vehicle armor ("tanks are sent cartwheeling, or are pulverized by concussive blasts"), but Space Marine armor can still save its wearer. A Storm Eagle warhead is incapable of destroying a vehicle outright due to the way the game works (unless said vehicle is open-topped, but there we're getting into a whole different kettle of fish), but is more than capable of mission-killing one in short order since it can deliver multiple hits per shot.

Earthshaker cannons (mounted on Basilisk self-propelled artillery) deliver more-or-less conventional high explosive shells, and kills power armor dead. Not coincidentally, it's also very good at wrecking vehicles.

The standard battle cannons found on most Imperial main battle tanks also deliver conventional high explosive ordnance that kills Marines dead over a large area. It is also passably good at wrecking vehicles. The description of the Vanquisher battle cannon variant pretty clearly describes HEAT shells, and though it doesn't make a big blast, if one hits an infantry soldier, that guy is dead barring force field shenanigans.

The Eradicator nova cannon is the aforementioned fly in the ointment; I'll just quote the entry directly. "Firing shells that contain a sub-atomic core, the Eradicator nova cannon is especially useful during sieges and urban warfare. Though it lacks the punch of more conventional ordnance, the shockwave produced by its shells' detonation is impossible to hide from, pulping even the most dug in enemy infantry." I have little idea what that's supposed to mean re: the mechanism behind how it works, but it pretty clearly describes a heavy, concussive blast, and yet unlike the heavier conventional ordnance, it does not easily penetrate power armor.

The Demolisher cannon, meanwhile, is essentially an anti-everything direct fire howitzer. It's huge bore (with shells described as three times the mass of standard battle cannon ammunition), short barreled, and is by far the most destructive weapon in the arsenal if it can be brought to bear (being extremely short ranged compared to everything else mentioned so far).

So what all this can tell us is essentially that the best way to kill a Space Marine is to drop a great big high explosive shell on his chest.

[U.P. Cinnabar]

Most of the things you can reliably kill a Space Marine with on the tabletop are in fact antitank weapons, and function rather well as antitank weapons. If you're Imperial Guard and you want to shoot down some guys in Marine armor? Fire a volley of antitank missiles at them. Open up with heavy energy weapons- the Guard has at least three different kinds of man-portable beam weapons, all of which have even better penetration than their missiles do. All those antitank weapons will cut through Marine armor like it wasn't there. They're also the same weapons that the same Guard formation would use to engage main battle tanks.

Or rare items such as the Cadian-pattern hellgun and the hotshot volley gun. I'm thinking the Type XIV Lasgun(Heavy) carried by Krieg Death Corps Grenadiers can also penetrate powered armor, but I can't find anything that says that for sure.

[Rogue 9]

Death Korps Grenadiers are essentially storm troopers and armed as such, so yes, they do act just like hellguns. But that's an infantry rifle, and one the Abrams doesn't have any equivalent to.

I don't think it's too terribly unreasonable to believe that 40k weapons are significantly more advanced than modern ones, though perhaps by less than one would think thanks to the Imperium's ten thousand years of technological regression. In any case, the guns on a Leman Russ tank are stupidly big. But their equivalent of HEAT beats Terminator armor with ease. I'm very confident that a modern MBT would be able to put down a Space Marine if the crew knew what they were up against and behaved accordingly.

[Sea Skimmer]

Certainly you'd hope they'd be more advanced. But when your talking about one of them, in contrast to a gun that weighs 2,600lb in the barrel alone and about 7800lb overall, it is very relative. A Space Marine is officially what 700lb or something? Certainly round that up to even 1,400lb with weapons and equipment if you want, but how much combat power do you really expect to get out of this? Tanks carry around thousands of actual pounds of actual ammo.

Its still just a big guy, so big he is a much easier target then a simple rifleman, but he's competing against something with several times his mass just in main weapon. And not some slow firing ponderous thing, its a weapon a man can load every four seconds, and with enough kinetic energy behind it that even if the Marine was immune to penetration he'd probably be killed by the shock of the hit, and certainly very violently thrown around.How vulnerable space marines are to blast and concussion damage depends on how much real living tissue you think is left inside of them. A hard shell power armor suit doesn't provide much rattle space, but the guys are so chopped into cyborgs its hard to tell what kind of internal shock hardening they might have.

The 40K guys are pretty good at being ultimate Marines, men who fight onboard ships, and make quick raids when called upon. But their value in a big armored battle is really not going to be that high, they'd have to be carefully put on built up terrine. The dreadnought help their total firepower, but they really don't carry much ammunition either for heavy weapons. Like the missile one has eight missiles. That competes with an armored hummve more so then a tank or artillery.

Imperial Guard troops aren't worthless since they have a semblance of combined arms, but they aren't coherently armed to fight a specific threat or just generate maximum firepower. It's very scatter shot. Also biased by the same problem Star Wars has of authors usually don't or can't deal with the kinds of numbers of troops that are being thrown around in 40K. The Marines could be incredibly effective and should still be quickly overwhelmed by mechanized armies because as good as they might be, they shouldn't be better then enemy armored hummer swarms with 40K tech equivalent 25mm guns and missile launchers in the open. Said vehicle is also only 6ft tall not counting the weapon mount, and Space Marines are about 8ft right.

The absurdo training is kind of la la land after a point meanwhile, were led to believe these guys have such absurd levels of cybernetic everything enhancement it's kind of hard to see why it should take them more then a few years of practice to reach the ~90% mark. You've got a computer now to do things like MAKE your brain check corners ect... Most training would probably come down to cooperation stuff, the same as it is for tanks and all arms, and even that might be far simplified by memory enhancements. Depends how you interpret things I guess, but this is totally the bluster end of Space Marine lore.