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It apparently has a lot of kick right out of the barrel, and then the secondary propellant on top, which is what gives it its penetrative ability.

The former is harmful to unmodified humans, according to numerous sources.

Bolter rounds just seem unnecessarily complicated. There's the charge which launches it like a normal bullet, then a rocket motor for extra velocity and then an explosive charge in the warhead. You don't really need more than two of those; if you are so desperate for velocity that you have two separate propulsion systems, you are probably trying to get good penetration. Switching your armour-piercing-explosive warhead for a shaped charge or explosively formed penetrator will give you that without needing to mess around making your projectile really fast.

 Desubot wrote:

 SharkoutofWata wrote:
Remember that the Bolter round has a secondary propellant after it leaves the barrel. Most of the projectile velocity would come from that. I'd actually imagine MUZZLE velocity would be lower than the velocity the round impacts at. But otherwise, yes. It is a rocket propelled grenade launcher after all. Not sure if we actually have an equivalent of that yet.

it should buut IIRC there are instances where untrained people that try and fire it break there wrists and stuff.

IIRC, you can break your wrists with a large calabre modern revolver.

There are RAP artillery rounds which have rocket engines.

 Perfect Organism wrote:
Bolter rounds just seem unnecessarily complicated. There's the charge which launches it like a normal bullet, then a rocket motor for extra velocity and then an explosive charge in the warhead. You don't really need more than two of those; if you are so desperate for velocity that you have two separate propulsion systems, you are probably trying to get good penetration. Switching your armour-piercing-explosive warhead for a shaped charge or explosively formed penetrator will give you that without needing to mess around making your projectile really fast.

It's pretty good. The rocket assistance gives longer effective range, higher accuracy and higher penetration when compared to other weapons of similar size. HEAT warhead would make no sense, since the standard bolt is designed to explode after it bypasses the armour.
Shaped charge would only leave you with a neat little hole.

 Finlandiaperkele wrote:

 Perfect Organism wrote:
Bolter rounds just seem unnecessarily complicated. There's the charge which launches it like a normal bullet, then a rocket motor for extra velocity and then an explosive charge in the warhead. You don't really need more than two of those; if you are so desperate for velocity that you have two separate propulsion systems, you are probably trying to get good penetration. Switching your armour-piercing-explosive warhead for a shaped charge or explosively formed penetrator will give you that without needing to mess around making your projectile really fast.

It's pretty good. The rocket assistance gives longer effective range, higher accuracy and higher penetration when compared to other weapons of similar size. HEAT warhead would make no sense, since the standard bolt is designed to explode after it bypasses the armour.
Shaped charge would only leave you with a neat little hole.

It would only have higher accuracy and better range if it was computer guided. and at that IIRC rocket motors are slower than most bullet speeds anyway. and they have to hope that the rockets burn evenly otherwise it could offset the weight of the shell as it travels even with fins.

I don't think it will really extend the range at all. Bullet drop will stay the same, so it has the same travel time.

The warspirit of a bolter, paired with the targeting auspex in a Space Marine's helmet does permit in-flight correction. Also, a rocket is slower than a standard bullet only if it is already traveling slower than a bullet. A bolter is not.

Does it have lift? Does it have thrusters on the bottom of the bullet to keep it up? If is doesn't then to will not travel further than any other bullet going the same speed. It's simple physics. An RPG sill has bullet drop.

Yes, that's part of the function of the finned band at the base of the round, which provides gyro-stabilization from the rocket thrust. With micro-adjustments in flight (again due to link between "war spirit" and targeting auspex) the round can make course-corrective adjustments while in transit.

It's not, obviously, going to make a 90 degree turn or anything (though, having said that, I'm sure BL will publish that eventually), but adjustments to flight ballistics are not out of the question.

But how? I can see left and right, but up would be quite hard to achieve without flipping the round.

I guess I'll have to put it down to space magic as usual (damn writers who don't know physics *muttermutter*).

1. Round is spinning via rocket-thrust from finned band around the bullet.

2. Warspirit says "we need to lift the nose 1.01 degrees"

3. Warspirit closes certain fins in band, causing rocket thrust to only eject from the "bottom" area of the band for a few microseconds.

4. Lift achieved.

5. Warspirit re-opens the vents to maintain flight stability.

I still think that would cause the bullet to flip. Although, for all we know, there could be a mini anti-grav generator in there!


I do, however, think that bolters could be a much better weapon if you made it not self propelled, extended the length of the barrel to more like a rifle, and replced the elcectronics with more explosives. Maybe that the reason bolters seem to be more powerful in 30K .

 Co'tor Shas wrote:
I don't think it will really extend the range at all.

It increases the velocity of the projectile beyond its normal muzzle velocity*, so you will end up with less time to target and less bullet drop.

* Logically, the design of the bolter would be to be "a best of both worlds" compromise between conventional and rocket propulsion. The conventional propulsion gives you a decent muzzle velocity (so it's useful at short range), but the rocket propulsion is recoilless. (And recoil energy is quadratically proportional to muzzle velocity, so offsetting even just a bit of the muzzle velocity is a massive reduction in recoil).

It's actually one of the most practical ways I can think of to get a large projectile up to high velocity without excessive recoil. It's less of a concern when wielded by an Astartes, but the bolter is an STC design that far predates Space Marines. The original designs were almost certainly put together to provide a weapon that was both powerful enough to kill Orks, but also be within the recoil levels a normal human could handle.

I'd reckon that the weapons used by Cultists, Gangers and Arbitrators are the closest equivalent to modern firearms we're going to see in the 41st millennium. And even then, you have crazy stuff like the Ripper Pistol and the Meathammer.

 Co'tor Shas wrote:
I still think that would cause the bullet to flip. Although, for all we know, there could be a mini anti-grav generator in there!


I do, however, think that bolters could be a much better weapon if you made it not self propelled, extended the length of the barrel to more like a rifle, and replced the elcectronics with more explosives. Maybe that the reason bolters seem to be more powerful in 30K .

We have modern ammunition today that can do that- if not possibly even better then Bolters. DARPA hopes that someday it may even be able to design bullets that turn corners.

Huh. Well, my knowledge of physics and aerodynamics is only slightly above average, so I'll have to check that out. Be interesting to see how they do it.

 Co'tor Shas wrote:
Huh. Well, my knowledge of physics and aerodynamics is only slightly above average, so I'll have to check that out. Be interesting to see how they do it.

Nobody knows. EXACTO ammunition has no guidance fins, and DARPA won't talk about how it actually moves to my knowledge. Probably some kind of funky gyroscope motor that spins to change direction or something.

That is awesome!

why does it need to be rocketpropelled? because recoil would be too high for automatic fire, in case of humans.
For marines it doesnt make much sense imo... they are strong and their armor enhances it even further, so dealing with recoil wouldnt be the big issue you would think...
The only other reason would be barrel length - bolter barrels are ridiculously short (guess because close quarters), so even if you put alot of powder in the round, it won't give alot of benefit plus create a gigantic muzzle flash.

As Marinebolters are propably larger (they have bigger hands after all), they can fire more powerfull rounds. The caliber is just the caliber. 2 rounds with same caliber can have vastly different properties.

Just compare the PomPom ammo (40x158) to the 40mm bofors round (40mmx311) or the even larger one