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The bolter is a small rocket assisted projectile.

A conventional charge kicks the shell out of the barrel. The rocket motor then ignites to boost the shell to a higher velocity. It has an explosive warhead.

It is basically a miniaturised version of the RAP artillery rounds of the late 20th century.

The slight problem I've generally had with the "rocket" idea is that even with fin stabilization - a rocket is not especially accurate from what I've heard (and read about on the 'net.) That's one reason why alot of "extended range" munitions using rocket assistance have to be guided. Maybe bolters have some laser targeting thing that allows them to home in on the target but I kinda doubt that.

There's also the recoil issue. (I could mention casings, but that could - hopefully - just be dismissed on the grounds of artwork).

Also: bolters are never going to have an exact parallel in real life because we've never made a bolter. It's like trying to find a RL parallel to a Chainsword or a Titan. Bolters as a weapon borrow from alot of different concepts (all of which have been mentioned) but are not defined by any one particular category. That's probably one of the reasons why they are so hard to make and high maintenance. It's not a weapon for practicality (although they can be reliable and durable if well crafted) - its a weapon for power and noise and psychological effect (again like a chainsword.) That's why its an iconic weapon of the Space Marines.

Bolters are rifled and use the gyro-stabilization.

the combination should increase the accuracy.


besides, the bolter is meant to be used at close range. Its not a rifle, its an assault weapon.

If the propellant fires off inside the barrel, then yeah it would. But once it leaves the barrel its going to have the same stability problems you get with rockets (you would need fins. I've never heard of fin-stabilized bolter rounds being common and I'm not even sure you can use fin stabilization with rifling either.)

I belive the rocket engine fires propellent out small stabilizing vents on the side(angled to give it a spin) as well as out the back. And then there is the normal rifling in the barrel to give it a spin to begin with.

Yeah, I've heard that too. but I've also heard that doesn't work. For one thing the constant thrust is constantly messing with trajectory which makes accuracy problematic - I don't think rockets stay perfectly "straight" in flight ( even when you spin them. Besides, having the stabilizing vents would pretty much negate the whole purpose of having rifling - gyrojets did this and they didn't have any rifling that I recall. I understand it even gets worse when you factor in conditions like winds.

That's one reason (as I understand it) alot of modern rocket assisted or rocket propelled artillery need guidance to get any real accuracy at range (contrast it with something like MLRS)

Edit: Foudn this link here

However, the RAP system has a number of known disadvantages, since even minor changes in ignition time and rocket power cause considerable changes in range. It is difficult to control the exact point of ignition of the rocket charge which concomitantly causes difficulty in controlling the trajectory of the projectile. RAP-projectiles, even when seemingly otherwise similar and fired from the same point, land in a relatively widely dispersed area.

I'd actually say most bolters probably do use a "rocket" but its designed to fire inside the gun, allowing the propellant to be confined by the barrel and build the initial velocity (hence bolter's having noticable recoil) to offset the issues of accuracy and wind. It probably would also explain the rifling. Maybe they keep burning a bit longer out the barrel to add spin and velocity (like a gyrojet). If its already spinning and has built up some velocity the accuracy problems could be reduced.

Besides bolters are also noisy weapons.. I'd expect they'd have to emulate regular projectile weapons to some extent to be noisy (at least if the info on gyrojets we have is reliable. That's the problem with failed concepts, sadly.)

Well, we know for a fact the rocket in the round burns during flight.


As for accuracy, we could assume the bolt has inbuilt guidence systems to keep it on target. In this case it just keeps the bolt on a straight path with no deviation.

The Mad Tanker wrote:

Lynata wrote:Bolters aren't gyrojet weapons.

Here's your real life bolter:




All you need to add is a rocket motor to the projectile and you're done.



18.5mm, so caliber 0.73, almost like the real thing.

When I saw it on the history channel, first think i though was "Its a bolter!"

Record that sound and play it off yyour phone if you've got to roll for Marines shooting

Connor MacLeod wrote:The slight problem I've generally had with the "rocket" idea is that even with fin stabilization - a rocket is not especially accurate from what I've heard (and read about on the 'net.) That's one reason why alot of "extended range" munitions using rocket assistance have to be guided. Maybe bolters have some laser targeting thing that allows them to home in on the target but I kinda doubt that.

I guess this is just one of the things where we have to keep in mind it's all fiction - that said, maybe it's not impossible that the manufacture of such ammunition in the 41st millennium is so advanced that it eliminates the issue. A bolt round wouldn't need high-tech homing guidance, for example, just some small mechanism that notices every slight deviation from its path and then adjusts the fins to correct for it. Or the miniature rocket simply burns so so precise and even, the fins are crafted so fine, that the projectile simply will always fly in a straight line.

Connor MacLeod wrote:There's also the recoil issue. (I could mention casings, but that could - hopefully - just be dismissed on the grounds of artwork).

Recoil isn't an issue at all - if you go by GW's 2E Wargear book, bolts leave the barrel at low velocity; it's not after the round has left the barrel that the rocket motor ignites and propels it to the desired velocity. Given that we know there are subsonic bolt rounds ("Stalker" projectiles), speed and mass are roughly equivalent to what the AA-12 fires, so the recoil would be comparable. And the AA-12's internal recoil suppressors are sufficient to allow you firing them with a single hand, or even dual-wielding these beasts. Firing bolt weapons with one hand happens a lot in 40k, too, just look at the Commissars. Their bolt pistols use the same ammunition as boltguns, and I've never seen any miniature hold one with both hands. Boltguns also lack a firing stock in general, which would be the first thing you'd add if you wanted to reduce the effects of recoil, in turn prompting me to believe there just aren't any (problems, not recoil - I actually like the thought that these guns still have some kick).

Also, what's the problem with casings? They do increase ammunition lifetime and reliability a lot!

There wouldn't be any noticeable recoil to a SM (even thought it's noted that they do feel a kick from the gun) primarily due to the armor/recoil compensators built into the gun itself/SM physique.

If a Guardsman used it, he'd need to brace and walk the weapon up the target, no way he'd be able to full-auto something like that.

As for the projectile, it's sort of hard to figure out how a bolter works. Given that the propellant/weight/explosive make is something completely alien to us. Not that I know munitions to the degree some in this thread do, but wouldn't the 'bolt' be reminiscent of a bunker-buster rocket or it's modern-day equivalent?

Note: I forget where I read it, but in one or more novels the 'guidance' mechanism for a bolt is described as gyro's INSIDE the actual round. Now if that's total crap, I'm not surprised. If it's not...man, that would SUCK to be the guy making bolter rounds.

I like to think of it as a bullet fired by primer and gunpowder and shortly after the gyro inside the bullet gets activated well outside the barrel of the weapon.

I also think of the Bolter to either explode on impact if hitting a hard surface or to explode once inside a soft target.

5 years is a pretty epic thread necro

Yes, indeed!

Please check the date on the last post in a thread before adding something - thanks!