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 n0t_u wrote:
Why do bolters have slides on both sides as well.

Allows both left and right handed users. Since marines are ambidextrous this would let them switch firing hand depending on circumstances or what each marine favors.

i know that you can get various types of ammunition for a bolter, perhaps some types have shells and others don't. also imo a base with spent casings looks really cool

locarno24 wrote:
Whether bolter shells are caseless or not has varied wildly throughout the history of the books and codices.

Regardless, Insaniak is correct - even a caseless round will need ejecting occasionally to clear a jam or other misfire.

This was actually one of the big original selling points, and ultimate pitfalls of caseless ammunition. Since they were caseless, you didn't need an ejection cycle and could cut that part out of the firing cycle entirely and get a resulting notable increase in rate of fire and remove another point of entry for foreign matter into the internals of the gun. That was the big selling point of the concept.

The problem was, yes it made it very difficult to clear jams and misfires, but also, almost as important, brass cases absorb a lot of heat from firing, and their absorbing of that heat and subsequent ejection from the gun actually plays a major role in heat management, and as a result caseless weapons tended to overheat very quickly.

However, reintroducing some sort of ejection mechanism to resolve these issues largely defeated the reason you'd bother with caseless ammo in the first place aside from ammunition weight reduction.

Bolters are a .75 calibre multi-stage munition. It has a standard cased shell protecting the initial chemical explosion that propels the round down the barrel (providing lethal velocity at the muzzle) and then a self-guided gyrojet rocket that engages at some distance later that can guide itself to the target based on the auto-senses and targeter in the Marine's helmet.

The round is armor-piercing and equipped with a mass-reactive explosive, meaning that the round explodes a split-second after its armor-piercing tip detects that it has entered an object. This explosive effect causes massive wound cavities and almost-certainly-lethal tissue and organ damage, not to mention wound-shock and blood loss.

Funny, every time I think of a "rocket gun" I think of the one from the movie "Runaway" .


Video of bullet in actionI would think of the casing as protection for the relatively delicate propulsion jet on the shell.
Heck, using an initial "classic" powder charge to light the fuse to accelerate it faster would be neat and then propellant for distance.
Not that we talk of Marines hitting targets a couple km's away.

Beaten to it by Calgar's Pimp Hand.

Bolters were originally caseless, but this part of the fluff was retconned in early 2nd edition. Bolters are not caseless. They have a normal casing which fires a bullet which has a self-contained rocket inside the warhead.

 jreilly89 wrote:
Because keeping gak straight is hard. Everything varies from author to author, aside from the fact that everyone wants to be an Ultramarine. The whole point of the Horus Heresy was that Horus was so mad he couldn't be an Ultramarine, he turned traitor. :

WAAARRRRDDD!!!!!

Andy Chambers recently covered this subject in an interview (can't remember which one, sorry!). He stated (paraphrasing) that Bolters were originally intended to be caseless, recoiless mini rocket grenades that sped up as they flew towards their target, based loosely on gyrojets that had been in the news at the time. However, their artist (I forgot the name) wasn't aware, and draw Marines leaning into the firing Bolters that had ejecting cases. Everyone loved the art, so the implied recoil and casings eventually replaced the recoiless, caseless original concept. If you look back to the older Bolter rules, they use to have a damage chart based on range, with more damage the further away the target was.

SJ

 Vaktathi wrote:

locarno24 wrote:
Whether bolter shells are caseless or not has varied wildly throughout the history of the books and codices.

Regardless, Insaniak is correct - even a caseless round will need ejecting occasionally to clear a jam or other misfire.

This was actually one of the big original selling points, and ultimate pitfalls of caseless ammunition. Since they were caseless, you didn't need an ejection cycle and could cut that part out of the firing cycle entirely and get a resulting notable increase in rate of fire and remove another point of entry for foreign matter into the internals of the gun. That was the big selling point of the concept.

The problem was, yes it made it very difficult to clear jams and misfires, but also, almost as important, brass cases absorb a lot of heat from firing, and their absorbing of that heat and subsequent ejection from the gun actually plays a major role in heat management, and as a result caseless weapons tended to overheat very quickly.

However, reintroducing some sort of ejection mechanism to resolve these issues largely defeated the reason you'd bother with caseless ammo in the first place aside from ammunition weight reduction.

It's rather telling that the first practical caseless firearm, the H&K G11, had an ejection port on the bottom in case of misfires. The G11 also had to use specially-developed low-sensitivity explosive compounds to mitigate the factor of heat buildup. Funnily enough, the US military purchased most of the G11 technology for use in their ongoing efforts to find a 100 percent superior replacement to the M16/M4 series of weapons. Even then, they've gotten a lot farther with cased telescoped ammunition, which is what I believe bolters are.

 jeffersonian000 wrote:
Andy Chambers recently covered this subject in an interview (can't remember which one, sorry!). He stated (paraphrasing) that Bolters were originally intended to be caseless, recoiless mini rocket grenades that sped up as they flew towards their target, based loosely on gyrojets that had been in the news at the time. However, their artist (I forgot the name) wasn't aware, and draw Marines leaning into the firing Bolters that had ejecting cases. Everyone loved the art, so the implied recoil and casings eventually replaced the recoiless, caseless original concept. If you look back to the older Bolter rules, they use to have a damage chart based on range, with more damage the further away the target was.

SJ

If that's the case, it must have happened pretty early in development, because the description of the bolt gun makes no mention of caseless ammunition. It's possible that happened, or it's also possible Andy misheard something, as the game had been in publication for two years before his first WD article (which was for Epic, anyway).

[quote in rogue trader, Rick Priestley et al]Bolt gun The bolt gun, also known as the bolter or blaster, fires small bolts or shells having explosive armour piercing tips. Bolt guns are popular with criminals because they make a loud, violent and suitably satisfying noise. For the same reason they are also poular with Orks - and represent the most common weapon used by those loathsome creatures.

I like to think of them using shells.

 n0t_u wrote:
Why do bolters have slides on both sides as well.

My SPR has an upper similar to that. It allows more powder to escape the chamber. It can be setup to eject shells on either side to allow for left handed shooting. It has a charging handle on each side in case one breaks off or you lose function of a hand/arm in combat. There's plenty of reasons for it.

 n0t_u wrote:
Why do bolters have slides on both sides as well.

So that if the SM's arm is blown off, he can pick up the gun in his other hand and cock it with his teeth.

Given that conventional guns can achieve a 20 round per second rate of fire, there is no need to use caseless ammunition to increase the ROF. The main advantages of caseless rounds are lighter weight and bulk, and reduced cost (no metal cartridge to be manufactured.) The practical disadvantages of caseless are that the round is more vulnerable to damage in storage and transport, and the guns tend to overheat a lot faster.

Its obviously a lot of inconsistencies of fiction due to the people writing it not having that much experience with firearms and the magical wave of the hand of saying its a vast sci-fi fantasy setting. I'm just gonna chime in with some of my engineering experience in munition design.

"why is there an ejector slide on the side of the boltgun itself?"
Insaniak proposed that its due to the need to deal with jams and failures of the round and thats a good one but their could be other reasons. There have been a number of prototypes at different times for caseless weapons and they don't all approach it the same way. For example at least one prototype for a "caseless" firing weapon still had a brass base on the round to allow for an aggressive feeding of the round into the chamber. While it seems counter intuitive to the purpose of making a caseless weapon it improved reliability and with a smaller piece to eject its still a significantly reduced ejection cycle. More recently the Army and Marine's LSAT program created a prototype caseless machinegun it still retains an ejection for because its belt fed and has to have a place for the disintegrating links to go... And if you consider Chaos bolters it would imply that like many modern machine guns its optionally magazine or belt fed.

"Yeah I really can't imagine how a rocket gun would be particularly effective in real life, especially for a fighting force that is supposed to be all about precision and efficiency like the space marines are."
Rockets over conventional ammo allow for a greater degree of flexibility with control and warhead design. Bolters are suppose to be semi-smart weapon with a variety of micro-warhead capabilities, many of what are described could only be accomplished with it being rocket propelled.

That said, I believe its in the 3rd edition rulebook, that a Bolter is explicitly described as a .75cal gyro stabilized gun, that would make it just over 19mm. Obviously the rounds have been depicted with the same distorted heroic scale perspective and are shown to be massive ridiculously proportioned shells. 75cal to 1" diameter is probably a realistic range for producing a munition that does what a bolter does and when you adjust heroic scale to a realistic scale makes for a feasible weapon profile.

When you look at a bolters design even after adjusting for "heroic scale"... there's a lot of empty room within the gun's shell. Likely their'd be alot rugedized computer built into it for iit to do all the things it claims to do. Given the futuristic nature of it all, I wouldn't be surprised if a Bolter additionally had electro-mechanical systems that did things like automatically clear jams, monitor and relieve barrel pressure, or a myriad of other things that would effectively make the wepaon more idiot proof.

I think the most reasonable explanation for a Bolter that fits the fiction and would be a realistic approach and a technological accomplishment... A Bolter is a large overarching class of weapons whose design allows it to accept a variety of ammunition from a variety of sources and function robustly and with few malfunctions. Consider just on Earth present day the differences in manufacturing and quality results in having to tune in weapons to ammunition or in some cases a complete inability to use particular ammunition. Now consider a galaxy wide manufacturing infrastructure with variable metal compositions, sophistication of design, and scalability... where conceivably a Bolter might have to use ammunition from millions of different potential sources. So what if the Bolters jumble of features is simply a contingency to accommodate all or most of the bolter rounds produce anywhere in the galaxy. In some places some varieties of Bolter shells are caseless while in others they are conventionally cased, where sometimes they are rocket powered and other times more conventionally gun powder propelled.It guarantees that marines sent to the other side of the galaxy don't have to worry about ammunition availability when they get their despite the possibility of great variation.

 aka_mythos wrote:
Its obviously a lot of inconsistencies of fiction due to the people writing it not having that much experience with firearms and the magical wave of the hand of saying its a vast sci-fi fantasy setting. I'm just gonna chime in with some of my engineering experience in munition design.

"why is there an ejector slide on the side of the boltgun itself?"
Insaniak proposed that its due to the need to deal with jams and failures of the round and thats a good one but their could be other reasons. There have been a number of prototypes at different times for caseless weapons and they don't all approach it the same way. For example at least one prototype for a "caseless" firing weapon still had a brass base on the round to allow for an aggressive feeding of the round into the chamber. While it seems counter intuitive to the purpose of making a caseless weapon it improved reliability and with a smaller piece to eject its still a significantly reduced ejection cycle. More recently the Army and Marine's LSAT program created a prototype caseless machinegun it still retains an ejection for because its belt fed and has to have a place for the disintegrating links to go... And if you consider Chaos bolters it would imply that like many modern machine guns its optionally magazine or belt fed.

"Yeah I really can't imagine how a rocket gun would be particularly effective in real life, especially for a fighting force that is supposed to be all about precision and efficiency like the space marines are."
Rockets over conventional ammo allow for a greater degree of flexibility with control and warhead design. Bolters are suppose to be semi-smart weapon with a variety of micro-warhead capabilities, many of what are described could only be accomplished with it being rocket propelled.

That said, I believe its in the 3rd edition rulebook, that a Bolter is explicitly described as a .75cal gyro stabilized gun, that would make it just over 19mm. Obviously the rounds have been depicted with the same distorted heroic scale perspective and are shown to be massive ridiculously proportioned shells. 75cal to 1" diameter is probably a realistic range for producing a munition that does what a bolter does and when you adjust heroic scale to a realistic scale makes for a feasible weapon profile.

When you look at a bolters design even after adjusting for "heroic scale"... there's a lot of empty room within the gun's shell. Likely their'd be alot rugedized computer built into it for iit to do all the things it claims to do. Given the futuristic nature of it all, I wouldn't be surprised if a Bolter additionally had electro-mechanical systems that did things like automatically clear jams, monitor and relieve barrel pressure, or a myriad of other things that would effectively make the wepaon more idiot proof.

I think the most reasonable explanation for a Bolter that fits the fiction and would be a realistic approach and a technological accomplishment... A Bolter is a large overarching class of weapons whose design allows it to accept a variety of ammunition from a variety of sources and function robustly and with few malfunctions. Consider just on Earth present day the differences in manufacturing and quality results in having to tune in weapons to ammunition or in some cases a complete inability to use particular ammunition. Now consider a galaxy wide manufacturing infrastructure with variable metal compositions, sophistication of design, and scalability... where conceivably a Bolter might have to use ammunition from millions of different potential sources. So what if the Bolters jumble of features is simply a contingency to accommodate all or most of the bolter rounds produce anywhere in the galaxy. In some places some varieties of Bolter shells are caseless while in others they are conventionally cased, where sometimes they are rocket powered and other times more conventionally gun powder propelled.It guarantees that marines sent to the other side of the galaxy don't have to worry about ammunition availability when they get their despite the possibility of great variation.

Marines rarely have issues with supply quality due to their status. Also, supply lines in general aren't as big of an issue for them, due to their shock-and-awe, in-and-out method of waging war. The description you're providing for bolters--rugged and versatile--is more in line with how the Imperial lasgun functions. Boltguns are described in the fluff as being very cantankerous weapons, not the sort that could take varying qualities of unsanctioned ammunition easily.

 AndrewGPaul wrote:

 jeffersonian000 wrote:
Andy Chambers recently covered this subject in an interview (can't remember which one, sorry!). He stated (paraphrasing) that Bolters were originally intended to be caseless, recoiless mini rocket grenades that sped up as they flew towards their target, based loosely on gyrojets that had been in the news at the time. However, their artist (I forgot the name) wasn't aware, and draw Marines leaning into the firing Bolters that had ejecting cases. Everyone loved the art, so the implied recoil and casings eventually replaced the recoiless, caseless original concept. If you look back to the older Bolter rules, they use to have a damage chart based on range, with more damage the further away the target was.

SJ

If that's the case, it must have happened pretty early in development, because the description of the bolt gun makes no mention of caseless ammunition. It's possible that happened, or it's also possible Andy misheard something, as the game had been in publication for two years before his first WD article (which was for Epic, anyway).

[quote in rogue trader, Rick Priestley et al]Bolt gun The bolt gun, also known as the bolter or blaster, fires small bolts or shells having explosive armour piercing tips. Bolt guns are popular with criminals because they make a loud, violent and suitably satisfying noise. For the same reason they are also poular with Orks - and represent the most common weapon used by those loathsome creatures.

It was a recent interview, talking about something that occured almost 30 years ago. I see no reason to doubt it since it was art work differing from concept.

SJ

 asorel wrote:

Marines rarely have issues with supply quality due to their status. Also, supply lines in general aren't as big of an issue for them, due to their shock-and-awe, in-and-out method of waging war. The description you're providing for bolters--rugged and versatile--is more in line with how the Imperial lasgun functions. Boltguns are described in the fluff as being very cantankerous weapons, not the sort that could take varying qualities of unsanctioned ammunition easily.

This isn't a question of status or quality in a good or bad sense, I'm pointing out a realistic logistical issue that becomes amplified the larger the supply chain and the greater the number of production facilities you have. The status of Space Marines might guarantee they always have bolt shells, but even if they're always the best it doesn't guarantee they come from the same Forgeworld or from the same batch of materials. I wasn't even talking about unsanctioned ammo, but in all likely hood Chaos utilizes unsanctioned ammo to full effect.

When it comes to supply lines... there ships are likely able to carry ammunition to fight years and years and years, but at some point they have to resupply and what happens when they aren't near the forgeworld that supplies their homeworld? -They have to get it somewhere else. Ammunition has a shelf life and the fact that they can travel for so long and so far, fight a decade long campaign would only exacerbate the matter. The longer ammunition is store the more inconsistent it becomes, this is a matter of chemistry and the fact that the same volatility that makes a thing go bang means the minute its made a clock starts ticking for how long its good. Now consider the Chapters that have no homeworld.

Keep in mind when I say "quality" I don't just mean good or bad. Quality can be a matter of consistency. 40k isn't Star Trek, their isn't a replicator to guarantee everything is an exact copy of the next on a molecular level. Inconsistencies in every facet of a munition can alter its performance. For example just between metal ore and alloys being produced on different ends of the same continent they have variability; so with millions of planets across the galaxy they are going to have different geology dictating the composition of ores and ease in which different alloys can be made. Somewhere in the databanks of the Mechanicus would have to be repositories of all the different acceptable variations that a sanctioned bolt gun design can fire. Logistically to coordinate all the Forgeworlds producing bolt shells and guarantee they work with every bolter all being produced all over the galaxy is herculian and only in the realm of possibility if the weapon is versatile. All that versatility is necessary even with the most basic ammunition before we even get into the specialty rounds Sternguard and Deathwatch use. This sort of consideration is a realistic one. Consider NATO has a standard specification for 2 different basic cartridges 5.56x45 NATO and the 7.62x51 NATO and despite the intent of complete cross compatibility of ammunition between the 28 member states of NATO there are in fact 28 different recipes for the same two cartridges before even considering the ammo produced by global partners and non-members; even still about 1/3 of NATO members can't use the ammunition of at least one other NATO member. The worst case was the French, their FAMAS rifle being such an aggressive cycle that it can only accept steel cased ammunition.In the grim dark 40k universe I believe technologically they've largely over come these hurdles and I think for that to be the case means the Bolter has features incorporated into it to allow it to tolerate galactic levels of variety.

Even if a bolter is cantakerous, a bolter is rugged enough to survive countless battlefields and continue working as a relic a millennia after it was put into service. The care to which they have to be service only implies sophistication and not a lack ruggedness.

 aka_mythos wrote:

 asorel wrote:
snip

Fair enough. However, your suggesting that some variants of bolt are powder-only does suggest a quality lapse in the colloquial sense of the word. Whatever differences there may be between bolts, I think it's safe to say that all bolts use the same basic design principles.

i dunno if bio-acid shells follow the same design principles as an high explosive tipped or fragmentation tipped shell.

It boils down to the inconsistency between the fiction and the artwork. We see bolters ejecting casings so either one of those are wrong being cased or careless or they're both right and both exist. I have no reason to believe either one is wrong so I believe they are both accurate characterizations of a bolter and simply choose to believe that all bolt guns can fire both.

 aka_mythos wrote:
i dunno if bio-acid shells follow the same design principles as an high explosive tipped or fragmentation tipped shell.

It boils down to the inconsistency between the fiction and the artwork. We see bolters ejecting casings so either one of those are wrong being cased or careless or they're both right and both exist. I have no reason to believe either one is wrong so I believe they are both accurate characterizations of a bolter and simply choose to believe that all bolt guns can fire both.

What is this fiction that mentions bolters as caselss? The FFG RPGs, among other sources, explicitly call out bolts as having casings.

 stonned_astartes wrote:
I reckon, 380,000 years in the future, engineering would have far extended our understanding, in other terms, si-fi.

In 380,000 years we will have transcended our very understanding of what "physics" truly is.

 asorel wrote:

 aka_mythos wrote:
i dunno if bio-acid shells follow the same design principles as an high explosive tipped or fragmentation tipped shell.

It boils down to the inconsistency between the fiction and the artwork. We see bolters ejecting casings so either one of those are wrong being cased or careless or they're both right and both exist. I have no reason to believe either one is wrong so I believe they are both accurate characterizations of a bolter and simply choose to believe that all bolt guns can fire both.

What is this fiction that mentions bolters as caselss? The FFG RPGs, among other sources, explicitly call out bolts as having casings.

I know it was a staple of the core rule books description in the 1st thru 4th edition books appearing with a variety of technical readout style artwork in a number of White Dwarf magazines. I can't say for certain if its still consistently a part of the fluff.

Bolters have a lot of wasted space in them. I like mythos' point about there possibly being machine spirits/servo technology in the weapon that automates a lot of the environmental variables, user error, munition incompatibility, propulsion back pressure, hydraulic recoil dampening,etc.

It seems like bolts incorporate both rocket propelled and ballistic components. Clearly there is a "Bang" when the weapon is fired off, but like someone mentioned, Bolters have almost no barrels to speak of, so ballistics obviously have little to do with the accuracy of the weapon. The length of the rifled barrel directly influences the degree of stabilization on the projectile flying through it, and a six to eight inch barrel isn't going to do much for a 20mm round. (For comparison, a 25mm M242 Cannon has a 105 inch long barrel )

So it must be at least partially rocket propelled. Possibly the ballistic reaction is just to get the rocket out away from the weapon, to give it a wide margin of error to engage the rocket propulsion. With this idea, you could either have a caseless or cased projectile.

I'm imagining this as basically a 40mm shell with a Gyroget rocket inside of it

Edit: Check this out! 2300 Yards fired from a normal M320 grenade launcher. This munition has a normal primer, and engages at 8-10 feet after it leaves the barrel of the M320. It proceeds to the target using a high powered IR laser target designator.

http://www.defensemedianetwork.com/stories/successful-test-for-pike-40mm-guided-rounds/

If we have something like this in 2015, it's not impossible that in 380,000 years they could directly link the target designator to the Space Marine's HUD, and make the round smaller (obviously a bolt doesn't need to fly so far. Probably a big chunk of this munition is fuel and the rather massive HEDP warhead at the front)

Bolters shells have explicitly had a two-stage propulsion system since forever, which I'm fairly certain has already been mentioned in the thread multiple times.

asorel wrote:Bolters shells have explicitly had a two-stage propulsion system since forever, which I'm fairly certain has already been mentioned in the thread multiple times.

Yeah, its one of the glaring inconsistencies between different bits of fluff. Personally I think a 2 stage propulsion makes the most practical sense; an initial charge to guarantee short range lethality and a second stage to ensure long range accuracy and maintain that lethal velocity.

I find when a fictional setting presents you with seemingly contradictory information, if you want it to make sense you just have to accept both and pretend one instance is simply an exception to the rule. Working under the premise that a bolter is a sophisticated weapon relative to today with the ability to self adjust to different ammunition there may simply be one particular specialized bolt shell that is purely caseless with out a 2 stage design; something like silenced shells of the stalker pattern bolter which is used more like a sniper rifle for stealthy operations where leaving a spent bit of sci-fi-space-brass would be undesirable.

Captain Fantastic wrote:Bolters have a lot of wasted space in them. I like mythos' point about there possibly being machine spirits/servo technology in the weapon that automates a lot of the environmental variables, user error, munition incompatibility, propulsion back pressure, hydraulic recoil dampening,etc.

It seems like bolts incorporate both rocket propelled and ballistic components. Clearly there is a "Bang" when the weapon is fired off, but like someone mentioned, Bolters have almost no barrels to speak of, so ballistics obviously have little to do with the accuracy of the weapon. The length of the rifled barrel directly influences the degree of stabilization on the projectile flying through it, and a six to eight inch barrel isn't going to do much for a 20mm round. (For comparison, a 25mm M242 Cannon has a 105 inch long barrel )

So it must be at least partially rocket propelled. Possibly the ballistic reaction is just to get the rocket out away from the weapon, to give it a wide margin of error to engage the rocket propulsion. With this idea, you could either have a caseless or cased projectile.

I'm imagining this as basically a 40mm shell with a Gyroget rocket inside of it

The most precise number claims that bolters are .75cal, which is 3/4 of an inch in diameter or a little over 19mm. At that size its just larger than a 12 gauge shotgun shell, more precisely equivalent to antiquated 11 gauge in bore size. The shotgun analogy is actually good food for thought because...

Bolters are alternatively called "Bolt guns" I think this is a very important fact. When describing a weapon, a "gun" is more specifically used to refer to a smooth bore firearm like a shotgun as opposed to a rifled one. This is actually realistically important as when you launch a rocket propelled munition you don't want a rifled barrel you want a smooth bore. Rocket propelled munitions can steer themselves to a limited degree but that ability to course correct is severally hampered by the spin stabilization a rifling imparts. Its a physics problem, a rifle stabilizes a projectile with spin to raise the projectile's inertia and keep it going straight, but course correction requires a rocket to bleed off that inertia and use thrust to power through. So the less inertia the less energy is subverted to alter the projectiles course.

The M1 Abrams tank originally had a 105mm rifled cannon utilizing predominantly the kinetic energy of a direct fire projectile, but the design iteration M1A1 Abrams switched to a 120mm smooth bore cannon to accommodate guided munitions that no longer needed to be aimed so precisely and had more in common with rockets than the traditional cannon shells. So as small arms are slowly following the technological development of larger cannons we will see more and more smooth bore small arms firing guided munitions, like the XM25.

Could Bolter's be rifled?-Yes but the technological hurdles are orders of magnitude higher and it'd be a matter of needlessly taking an overly complicated route to accomplish what a bolter could do with less.

Captain Fantastic wrote:
Edit: Check this out! 2300 Yards fired from a normal M320 grenade launcher. This munition has a normal primer, and engages at 8-10 feet after it leaves the barrel of the M320. It proceeds to the target using a high powered IR laser target designator.

http://www.defensemedianetwork.com/stories/successful-test-for-pike-40mm-guided-rounds/

If we have something like this in 2015, it's not impossible that in (38,000) years they could directly link the target designator to the Space Marine's HUD, and make the round smaller (obviously a bolt doesn't need to fly so far. Probably a big chunk of this munition is fuel and the rather massive HEDP warhead at the front)

I think a hud linked targeting is achievable a lot sooner. I imagine on a rudimentary level a bolter combines the onboard targeting system of something like Tracking Points aim assist, with the reprogrammed munition of the XM-25, with guided course correction of the Pike... all in a much much smaller and more robust package. Its important to consider that the height of Pre-darkage technology far exceeded the Bolter and that the Bolter is simply the height of small arms technology after 15,000 year dark age and about 150 years of rediscovery. It's clear the bolter has a rail which a scope can be bolted to and if its like other modern emerging technologies, that rail probably provides wireless power to a powered optic that transmits targeting and telemetry data to the marines power armor allowing them to fire from the hip with the accuracy of a sniper.

I think the Pike is an amazing piece of equipment, in a decade it will probably replace the law rocket as the predominant point target munition. Obviously things may change after they do more testing but given the picture of it, its assembled as 3 primary sub-assemblies. The front is guidance and fuze package, the rear is the rocket motor, and the middle is the explosive load. Each section is roughly 1/3 of the Pike's, given that payload size this is carrying as much as 3-1/2 times as much explosives as the more conventional 40mm grenades. That the difference between clearing a room and destroying the room; disabling a vehicle and its passengers and completely destroying the vehicle. In all likelihood the space will be used for a variety of warhead and explosive loads with more tailored capabilities, but no doubt that most brute force version will be a favorite.

 AndrewGPaul wrote:

The real question is, after seeing that - at some point could all marines fly/jump, and not just assault marines? After all, that is a "jet pack".

I do not know much about the older lore.

 Ouze wrote:

 AndrewGPaul wrote:

The real question is, after seeing that - at some point could all marines fly/jump, and not just assault marines? After all, that is a "jet pack".

I do not know much about the older lore.

They are Space Marines, I imagine they have some zero-g capabilities beyond mag-boots, for those environments that don't have metal surfaces. Their power packs have been shown to produce an exhaust, most likely helium if its fusion powered, and that in a zero-g environment it can be released in controlled burst to steer a floating marine.

 Captain Fantastic wrote:
Bolters have a lot of wasted space in them. I like mythos' point about there possibly being machine spirits/servo technology in the weapon that automates a lot of the environmental variables, user error, munition incompatibility, propulsion back pressure, hydraulic recoil dampening,etc.

It would also take longer for a bolter to overheat thanks to the extra material. Maybe part of it is specifically built areas that conduct heat away from the barrel? If they're really tricky those massive magazines are also part heat sinks.

Well considering the real gyrojet weapons have a very low velocity BEFORE they leave the barrel it's likely there is a case to FIRE it up to high velocity like a multi stage rocket. So the casing is ejected and the bolt is traveling at a high speed already for close range, then the rocket kicks in for range/stabilization and impact force. Not to mention penetrating flesh and exploding once it's dug in.