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LukeValantine said:
Just wanted to point out how insane this statement was. Rocket propelled grenades by their very nature are a hell lot slower then rifle bullets, and no matter of sci-fi nonsense will change the fact.
I do agree with you but because started nitpicking I'll just have to say that grenades by definition are not propelled at all. Rockets are, and that's why they are called rockets ;)

I haven't studied the Space Marine fluff too intensely but the HH series speak nothing of those links from their visor to their guns. Might be post-heresy invention, though
 

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I actually just finish watching the crappy Space Marine movie (and it sucked bad) and sorry to bust everyones bubble but it is a Rocket propelled. In a slow mo shot of a Bolter round leaving the barrel shows the rocket activate launching it foward and then cutting out (and according to some BL novels activating the warhead) before hitting a CSM in the face. So......
 

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Just to clear up a few things:

Bolts are rocket propelled and are 'shot from the barrel under low velocities' - so, at close range it isnt going very fast, but as soon as it leaves the barrel the rocket ignites, so at medium to long distances it hits very fast. (second edition wargear book)

Bolter 'mags' are 20-30 rounds that are staggered so that explains why they are wider than a traditional magasin would be to account for the rounds being side by side. Drum mags carry 40-60 rounds and bolt pistols only manage 6-10 rounds. (3rd edition rule book).

Bolters ARE rifles and they DO have rifled barrels - there is a cut open picture of a storm bolter on page 60 of the third edition rule book with an arrow that says '0.75 calibur rifled barrel'

Bolter are also able to be fired from the hip because they have a direct link to to the marines autosenses and the sights on the barrel are always listed as 'back up sights'
 

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isnt there a sensor in the helmet that helps targeting? no reason to aim down the sights then...

thats why scouts do have to aim down the sights, they dont have helmets
 

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I do agree with you but because started nitpicking I'll just have to say that grenades by definition are not propelled at all. Rockets are, and that's why they are called rockets ;)
True however that fact is irrelevant, because do to the nature of bolts they are considered rocket propelled grenades (RPG's) and in fact are not grenade launchers in the purest sense (Do to the fact they have a secondary propellant).

However I should go back and make that observation clear in my original post to avoid confusion.

(RPG's also tend to be even slower then Grenade launcher, but do to the hybrid nature one would realistically expect a similar initial acceleration to a 30mm grenade cartage followed by a period of slowing down before the propellant kicks in to maintain acceleration.)

Also comparing a bolter to a real gun (In other words following the laws of physics and mechanics, thermodynamics ect. On would realistically expect the velocity of a bolter to be around 800f/s at the incredibly high end of probability, and more likely 600f/s.

In short grenades are not designed for velocity, and will have the penetrating ability of a .5 pound lead base ball. What makes them deadly is either the shaped charge at the tip, or for the common bolter round the HE tip. So no blowing holes clean throw things for any bolter round (Stupid ultra marines movie), although shaped charges are far better at penetrating armor anyways.
 

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It's interesting that the 3rd Edition Rules label it as a rifled barrel, but simple physics really eliminates this possibility for practical reasons. The process of engraving that a projectile must undergo to fit the rifling actually slows the projectile in the barrel; since the bolt is "shot from the barrel under low velocities," this would slow it down even more.

To get even a very low (and relatively unstable) twist rate of 1 in 60 inches, a .75 cal bolt would need to achieve a muzzle velocity in excess of 900 feet per second, which simply wouldn't be possible for a rocket propelled bolt fired from a short barrel (even if it could achieve those speeds, based on the size of the bolt the spiraling necessary for stabilization would be something like sixteen rotations in the barrel, which would necessitate a ridiculously long barrel). The net result is that the rifling would actually cause the bolt would yaw and become very inaccurate.

Since the Ultramarines movie has been mentioned, you can actually see in the movie that bolters aren't rifled and that the bolt itself appears to have some sort of rotary stabilizer below the tip.
 

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Discussion Starter #27
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.

here are some other examples:

When lifting something heavy, you can use your arms and jerk straight up with your back. I guess after 100 of years, if you haven't developed chronic back problems, you'd get pretty strong and capable. However bend at the knees and put your legs in the mix and omg! look at how much weight you can now lift!

your going to kick a soccer ball. Sure you can kick it with your toe, but it is more effective and more reliable to kick with the side of your foot.

You make a sandwich and decide to use a spoon to spread the peanut butter, but it will be 10x easier with a knife.

Do we get the picture?
 

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Well, it's easier to shoot from the shoulder because we line up the sights with our eyes and the shoulder absorbs the recoil. If lining up the sights with your eyes and recoil isn't an issue, I suppose it wouldn't matter if you shot it over your shoulder or under your leg, so long as you were practiced at it.
 

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Which SM are.

They are VERY practised at it.
It's pretty much what they do (all they do) when they are not "in ur base, killin' ur d00dz" (practise killing you better).

If you don't need to expose your head to shoot your enemy, you have a tactical advantage. With sights from the gun linked to your helmet with a HUD, You can point your gun around a corner and risk only your arm. This is pretty much part and parcel of the "Future warrior" concept and Power armoured warrior from the first instances of them.
 

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It's interesting that the 3rd Edition Rules label it as a rifled barrel, but simple physics really eliminates this possibility for practical reasons. The process of engraving that a projectile must undergo to fit the rifling actually slows the projectile in the barrel; since the bolt is "shot from the barrel under low velocities," this would slow it down even more.

Nothing in 40K fits with physics - hell they even have laser beams that 'bounce' off walls and are still lethal...

It says it is, therefore it is - sorry.
 

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Guess we will have to file it under the laz guns having recoil, and whole space knight thing.
 

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Nothing in 40K fits with physics - hell they even have laser beams that 'bounce' off walls and are still lethal...

It says it is, therefore it is - sorry.
I'll forgive you then and stick with what I know. :wink: After all, 40K is full of contradictions and retcons. BTW, what laser beams bounce off walls?
 

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I'll forgive you then and stick with what I know. :wink: After all, 40K is full of contradictions and retcons. BTW, what laser beams bounce off walls?
Happens in some of the gaunt ghost novels (If my memory serves).

When you start to use 'logic' and 'real world' examples for things in 40K everything starts falling down around you. Its just best to nod and smile and be 'self content' in the knowledge that you know more about physics than the black library writers. :biggrin:
 

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That and they apparently laz weapons have kinetic force, and don't behave like real lazers, because that wouldn't be cool enough. Blowing arms off? What did GW designers fail physics class or something.
 

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It's interesting that the 3rd Edition Rules label it as a rifled barrel, but simple physics really eliminates this possibility for practical reasons. The process of engraving that a projectile must undergo to fit the rifling actually slows the projectile in the barrel; since the bolt is "shot from the barrel under low velocities," this would slow it down even more.

To get even a very low (and relatively unstable) twist rate of 1 in 60 inches, a .75 cal bolt would need to achieve a muzzle velocity in excess of 900 feet per second, which simply wouldn't be possible for a rocket propelled bolt fired from a short barrel (even if it could achieve those speeds, based on the size of the bolt the spiraling necessary for stabilization would be something like sixteen rotations in the barrel, which would necessitate a ridiculously long barrel). The net result is that the rifling would actually cause the bolt would yaw and become very inaccurate.

Since the Ultramarines movie has been mentioned, you can actually see in the movie that bolters aren't rifled and that the bolt itself appears to have some sort of rotary stabilizer below the tip.
Bolts use a 2-stage firing system (which has been previously mentioned). A small explosive charge ejects it from the barrel, and this would also get it started spinning due to the barrel rifling. 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.
This also means there is some recoil, but less than you would expect from a .75 caliber round, as much of the acceleration happens after it leaves the barrel as well.
 

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Actually, if you think about it, if the round WASNT rotating when it left the barrel no matter how good those gyrojets were, it could go ANYWHERE. Sure, once they started firing they would guide the bullet in a straight line - but that straight line might not even be close to where they were aiming in the first place.

Anyone who has read up on non-rifled muskets will know exactly what I am talking about.
 

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That and they apparently laz weapons have kinetic force, and don't behave like real lazers, because that wouldn't be cool enough. Blowing arms off? What did GW designers fail physics class or something.
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.
 

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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.
However that wouldnt fit with the other things we know about lasguns - like the fact that the power pack can be charged using heat/electicity - so if thats the case - where do the pariticles come from for the beam?
 
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