[Dogbeard]

Theoretically, the particles themselves could be drawn from the air, if the technology was advanced enough; particle beams developed in the '80s used hydrogen.

Then after it leaves the barrel it ignites a secondary rocket propellant that actually carries it to its target, using the technology known today as Gyrojet (Wiki link here), which can use shaped nozzles to add more spin to the round without requiring fins or stabilizers.
The only thing the rifling does is get it started so that the jets aren't starting from a situation of no rotation at all. This means the barrel doesn't have to be as long as it would for a standard bullet.

You didn't actually read the Gyrojet article, did you? :wink: Rifling the barrel would cause severe problems, which is why the Gyrojet used vents for stabilization rather than rifling the barrel. Rifling fins could also work, though as I mentioned earlier, the bolt in the Ultramarines movie appears to have some sort of rotary stabilizer band.

 

[Anarkitty]

You didn't actually read the Gyrojet article, did you? :wink: Rifling the barrel would cause severe problems, which is why the Gyrojet used vents for stabilization rather than rifling the barrel. Rifling fins could also work, though as I mentioned earlier, the bolt in the Ultramarines movie appears to have some sort of rotary stabilizer band.

Not recently at the time of posting, no.

I just re-read it though, and while it mentions rifling is unnecessary, nowhere does it state that it it is detrimental or problematic.
In fact, in a case where a two-stage firing mechanism is used (explosive charge to eject the shell, then rocket to propel it over longer distances) the rifling would, in fact, become necessary to provide an accurate start to the shell's flight.

As for why this two-stage system would be used, my own theory is that it is to overcome the low velocities that rocket-propelled rounds suffer from at very close ranges, and the slow rate of fire compared to conventional ammunition. This allows the weapon to still be effective at point blank ranges and in close combat, and allows it to use a standard firing mechanism without the unreliable re-cocking mechanism and internal magazine of pure gyrojet firearms.

 

[Maidel]

You didn't actually read the Gyrojet article, did you? :wink: Rifling the barrel would cause severe problems, .

Actually - no it wouldnt - it simply wouldnt do anything (unless the barrels rifiling was trying to spin the bullet the otherway, in which case it might have some interresting results...)

The fact is, these work differently to bolters - the rockets fire in the barrel of these guns and the bullet spins in the barrel because of them.

A bolter fires the round first and the rocket fires after it has left the barrel - if the barrel was NOT rifled, then the bullet would fly out of the barrel and would probably start cartwheeling in the air (like musket bullets used to) and then when the rocket fired, well, it would be like piling up a stack of fire works and lighting them - they would go in all directions.

 

[hailene]

I think it's not one or the other, but rather pick your poison.

You could have a gun that shoots rockets with rifling. I think that's what recoilless rifles are. Most of them, anyway.

The gyrojet articles that 4 mini jets ignite while the projectile is still in the barrel. This creates the spin needed to keep projectile pointing forward and not tumble.

 

[Dogbeard]

Actually - no it wouldnt - it simply wouldnt do anything

Except go wildly out of control.

A RAP system is feasible, but while this will increase the range of the bolt, it will also greatly reduce its accuracy. The muzzle velocity of the bolter would also have to be higher, since the initial track and spin of the bolt would be determined by the barrel and propellant. Since the bolt's killing power doesn't rely on penetrating power or ballistic injury, its muzzle velocity can be much lower without effecting its performance; once the mass-reactive detonator is engaged, you could probably throw a bolt at a target with lethal effect.

Many recoilless rifles have rifled barrels (the term is often also applied to unrifled models as well, such as the SPG-9), but these necessarily fire their projectiles at a higher velocity down a long barrel. The idea of the bolter being more akin to a recoilless rifle than a Gyrojet is probably apt though.

If you want the bolter to be rifled, it's no skin off my nose. Cheers.

 

[Maidel]

Except go wildly out of control.

Im not trying to be arguementative - but why?

There is nothing in that article that says that and I cant find anything on a quick google search either. Its not my area of expertise - but I cant see why it would do that - if both the rifling of the barrel and the gyrojet (which remember in the bolters case only fires after it leaves the barrel) rotate in the same direction - why would it go wildy out of control?

If you want the bolter to be rifled, it's no skin off my nose. Cheers

Hey, its GWs fluff, not mine :biggrin:

 

[laviathan13089]

I actually remember discussing this on another forum a while back. Pure high-energy lasers would just burn a hole clean through a target, but lasguns could produce these effects if they were actually a sort of pulsed impulsive kill laser, which would quickly superheat the surface of its target to create plasma explosions and would have a strong mechanical effect on the target. Another possibility would be that lasguns are firing particle beams along a laser plasma conduit; this would deliver the kinetic force and the explosive reactions described in the codices and novels.

wouldnt that be a pulse rifle?

Another thing, what kind of propellent do bolt rounds use? how about the explosive tip? what kind of metal do they have? how much do they weigh? since all of these factors play CRITICAL roles in the physics/thermodynamics/aerodynamics of said bolt rounds. i feel like you all know something i dont, because if you didnt know any of these things and are guestimating based on current, crude, weapons... that would make you retarded, wouldn't it? :biggrin:

 

[LukeValantine]

Actually you can make a damn good guess at aerodynamics based on appearance, and size, and going on how gw has discussed how bolters work and released diagrams of how they roughly function we know that there is very little tech besides possible metallurgical innovations in a bolter.... in short yah we can make some damn good assumption on how a bolter would work in real life going on this info.

Also from the show instances of bolters firing the propellant is most likely a standard chemical propellant (Not much different from what we now have) most likely in a solid stat while the primary explosion is most likely basic smokeless powder.

 

[Dogbeard]

:goodpost:

Im not trying to be arguementative - but why?

I guess I am being sort of argumentative. The basic problem comes down to velocity and centrifugal force of the projectile. Once the rocket propellant ignites, there is also a shift in the projectile's center of gravity. Honestly, these problems probably could be overcome, but rifling the barrel would be introducing problems that wouldn't exist with a smoothbore barrel.

wouldnt that be a pulse rifle?

Not exactly, no. According to the Tau dex, it uses a "induction field [James Maxwell's magnetic quantity B] to propel a particle, which reacts by breaking down to create a plasma pulse as it leaves the barrel." This is a sort of particle beam, with the twist that the particles become highly ionized (probably through the ejection of electrons, hence "breaking down").

A PIKL is a high-energy laser that fires a series of ultrashort pulses on the order of picoseconds (one trillionth of a second) or even femtoseconds (one quadrillionth of a second); if in the visible spectrum, millions of these pulses would appear to the human eye as an uninterrupted beam of light. This seems to me like a really good candidate for the lasguns of 40K.

 

[Maidel]

Joy.

Everyone wants to argue with me today.

So, basically it is possible.

 

[Anarkitty]

Joy.

Everyone wants to argue with me today.

So, basically it is possible.

Yep, and yep apparently.

 

[Dogbeard]

But there's the rub. It's possible, but only if the bolt is fired from the barrel at relatively high velocity. Plus, you would still get yaw when the bolt rocket ignited out of the barrel, compromising its accuracy. As odd as it may sound, a smoothbore would be much more accurate if the muzzle velocity is low and the rocket ignites out of the barrel, as stated in the lore.

If you want to rationalize it, it's possible that only storm bolters are rifled (as shown in the 3rd Edition), to allow for increased penetrating power at very close ranges. Given the doctrine of terminators engaging at close range, this would make some sense.

 

[Speedo01]

I think their armour is too bulky to have the wearer look down the sight (look at mk 8 errant and grey knights aegis power armour), so maybe that useless inch wide sight holds a camera in it hooked up to the helmets interface.

couldn't they also curve the bullet?

 

[bitsandkits]

marines dont need to use sights or look down the barrel and all that shite for one simple reason... the rule of cool, you dont get cool points for using a weapon logically and effectively you get cool points for looking bad ass.
the whole point of 40k is to escape realism, not to encourage and abide by it.



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[Iron Angel]

http://en.wikipedia.org/wiki/Gyrojet

"The Gyrojet is a family of unique firearms developed in the 1960s named for the method of gyroscopically stabilizing its projectiles. Rather than inert bullets, Gyrojets fire small rockets called Microjets which have little recoil and do not require a heavy barrel to resist the pressure of the combustion gases. Velocity on leaving the tube was very low, but increased to around 1,250 feet per second (380 m/s) at 30 feet (9.1 m). The result is a very lightweight weapon."

In the 60s the bullets could reach almost 400m/s. Think what they can do 20000 years from now. Also they were more accurate due to gyroscopic stabilization and had extremely low recoil.

Thats how a bolter works. Its a big gyrojet machine gun 20000 years in the future.

 

[Aramoro]

Just making note. I do not care if they have an in helmet reticule to help aiming at the hip easier. It is still more effective to aim from your shoulder and down your sites.

Your example is inherently flawed as you don't know what kind of targeting software they're running. A pilot is not looking down the barrel of his gun when he fires, but it hits the target he's aiming at. Why? Because the software know he's not looking down the barrel of his gun and compensates.

You're imposing what is more effective for you, not for a Space Marine. You should not conflate the two as you're not a Space Marine.

I've you've never written software for targeting computers in jet fighters your argument is void.

 

[Magpie_Oz]

The only problem with not having the weapon into the shoulder is stability which has an effect not only on the individual accuracy of a given round but also the precision of a group of rounds.

Holding a weapon by your side is not stable because it is designed to be in your shoulder.

If however the weapon is designed to be held rock solid in a servo actuated suit of power armour and aimed by an off axis designator then it really doesn't matter where you hold it. Just like a fighter plane's machine guns in the wings, like Aramoro says.

 

[Insanity]

Just making note. I do not care if they have an in helmet reticule to help aiming at the hip easier. It is still more effective to aim from your shoulder and down your sites.

But that's the thing, the link from their helmet to their gun is exactly the same as looking down the sights. there is no difference. If they did hold the butt to their shoulder they would just be seeing the same thing as what is in their helmet. Which would look pretty weird as well.

 

[Magpie_Oz]

But that's the thing, the link from their helmet to their gun is exactly the same as looking down the sights. there is no difference. If they did hold the butt to their shoulder they would just be seeing the same thing as what is in their helmet. Which would look pretty weird as well.

They wouldn't actually see the view of looking through the sights tho' you'd just see a target reticule superimposed over your normal vision, like a heads up display in a fighter.