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Hi all

I came across this video and I though I would share. I started watching the In Range videos based on the Forgotten Weapons videos by one of the presenters. I find them all fascinating and informative about how firearms actually work.

Anyway in this video they do some live firing of ww2 era 8mm-ish explosive rounds into ballistic gel. Snipers on both sides on the Eastern front were apparently using this stuff. Yerg...

The results are pretty catastrophic and might help visualise the potential effects of an even larger round with more space for payload. Definately something I hope never to have to deal with in real life!

https://youtu.be/AXaaybiRiYY

Explosive rounds are still around today. More commonly found in 50cal size, so closer to what bolters would fire.

https://en.wikipedia.org/wiki/Raufoss_Mk_211

Bolters are canonically 0.75-cal, which is very close to 20mm.

So, a good analogue might be a 20mm grenade launcher- the Neopup PAW-20 is probably the best extant example. Here's a video of one firing live (explosive) ammunition.

As you can see the recoil is substantial, but it's still manageable in slow semi-auto by a human user. Throw in secondary rocket propulsion to boost the effective velocity and it's pretty much a bolter.

Good points all. I just hadn't seen a video before of explosive rounds in a biological equivalent material.and thought it was interesting, if pretty horrifying.

Also Forgotten Weapons has done a neopup video as well

https://youtu.be/QHbqHx3TLBE

 catbarf wrote:
Bolters are canonically 0.75-cal, which is very close to 20mm.

Not all - Godwyn pattern are 0.75 while Phobos are 0.70 and Tigrus are 0.60

I'm pretty sure most of the smaller ones are not meant for power armor users, though, and are more special issue inquisitorial equipment. Regardless, the "standard" is .75 with heavy bolters being a "standard" of 1.00.

there was a big thread about this a while ago. I still stand by my opinion that you wouldnt be able to fit all the components to have a round that has a rocket propelled secondary charge, inertia armed, impact delay explosive charge, into a bolter cartridge, even if they are .75mm...

Certainly not with modern miniaturization technology. But 40k doesn't use that.

Welcome to science fiction/fantasy.

indeed, but seeing as they still essentially using ww2 issue tank, aircraft technology, I've just applied that same logic to the scenario.

 queen_annes_revenge wrote:
indeed, but seeing as they still essentially using ww2 issue tank, aircraft technology

I didn't know we had laserguns, hovertanks, and plasmaguns in ww2! What a distant era of lost technology that must have been.

An open cylinder bore 12 gauge is almost. 75 in bore diameter, and there are explosive 12 gauge slugs, so the whole idea that bolters fire red bull can sized rounds is bull gak. An open cylinder 10 gauge would be bigger but obviously doesn't have the same kind of selection of rounds.

Yeah nowhere near that big. Even heavy bolter shells are only just over an inch in width.

 Melissia wrote:

 queen_annes_revenge wrote:
indeed, but seeing as they still essentially using ww2 issue tank, aircraft technology

I didn't know we had laserguns, hovertanks, and plasmaguns in ww2! What a distant era of lost technology that must have been.

Yawn. why not maybe try adding something constructive to the converstaion?

 queen_annes_revenge wrote:
Yawn. why not maybe try adding something constructive to the converstaion?

You first, kiddo. 40k has always been about strange technological and tactical anachronisms, since the very start. Saying "this kind of thing is impossible IRL" is pointless, irrelevant garbage.

Even assuming that technology hasn't progressed in the setting since the Heresy one would think that weapon technology had advanced beyond current standards in 28000 years.

A rocket round would be longer though as the proportion of propellant in the casing is reduced to basically enough to.get it out of the barrel.with the rocket kicking in after that. Also I recall bolt rounds being mass reactive rather than impact armed, so.that would probably help with miniaturisation

 Melissia wrote:
Certainly not with modern miniaturization technology. But 40k doesn't use that.

Welcome to science fiction/fantasy.

I figure it's mostly a matter of finding an explosive that has enough yield. And since this is a world where fairly large ships can take off from 1 G planets without having to drop any sections, it's safe to say that they have found that explosive. (Perhaps promethium, whatever it's made of.)

Pretty much all of science fiction runs on some kind of unobtainium.

Bolt rounds are just flechette rounds that replace the inert flechette with a mini rpg. Certainly not something that we’ll see on an actual battlefield anytime soon but bolt rounds are a pretty minor suspension of disbelief compared to a lot of other stuff in 40k.

 queen_annes_revenge wrote:
indeed, but seeing as they still essentially using ww2 issue tank, aircraft technology, I've just applied that same logic to the scenario.

See, there's your problem right there.

Canonically they also have grenades the size of marbles and "planes" that happily fly into space.

Well the grenades on the space marine models look like Mills grenades to me, again, ww2 era tech.


Automatically Appended Next Post:

Prestor Jon wrote:
Bolt rounds are just flechette rounds that replace the inert flechette with a mini rpg. Certainly not something that we’ll see on an actual battlefield anytime soon but bolt rounds are a pretty minor suspension of disbelief compared to a lot of other stuff in 40k.

I have no problem suspending my disbelief, but it's so inconsistently applied too. For example, you'd need some kind of inertial arming for the mass reactive charge, similar to that used in weapon launched grenades, but the books have them exploding in peoples heads after being fired execution style and all other sorts of craziness. Its minor details, but as an explosive technician it's things I notice.

Gadzilla666 wrote:
An open cylinder bore 12 gauge is almost. 75 in bore diameter, and there are explosive 12 gauge slugs, so the whole idea that bolters fire red bull can sized rounds is bull gak. An open cylinder 10 gauge would be bigger but obviously doesn't have the same kind of selection of rounds.

Yeah this is possible right now. This video is a little dramatic, but it demonstrates the frag 12 round which is very close to a bolt round, although it uses the propellant to travel rather than an inbuilt rocket.

https://m.youtube.com/watch?v=WV379084djs

Back in some early 40k pics the bolts had really short cartridges, stubby little ones which makes sense to me as they are only used to push the round out.

One thing I think people really don't appreciate about advocating stupid sized bolts is that it makes the magazines TINY.

A 1 inch bolt stacked in alternating overlap (let's say 50% overlap), means that every 2 rounds equals a vertical distance of 1 inch. So 30 rounds is 15 inches long, which is a one and a half foot long magazine. That's ridiculous by itself. A 0.75 cal stack of 30 is still ~11.5 inches, which is almost a foot long. Now this is assuming that they stack this way.

Any bigger than this is going to make the magazine capacity small, or the magazine's stupidly long.


It's one of my cosplay pet peeves that people make stupidly oversized bolters with muzzle diameters so large the corresponding magazine could Only hold like 4 rounds....

Muzzle diameter isn't always, or even usually, indicative of the bore diameter in military grade weapons. They'll have thicker barrels for heat absorption, so the muzzle ends up flaring quite a bit.

 Veteran Sergeant wrote:
Muzzle diameter isn't always, or even usually, indicative of the bore diameter in military grade weapons. They'll have thicker barrels for heat absorption, so the muzzle ends up flaring quite a bit.

While that's true,. There's a difference between that and what people have done:

https://www.thingiverse.com/thing:2138894

https://designedby3d.com/shop/bolt-pistol-cosplay-prop-from-warhammer-40k/

https://www.etsy.com/listing/560692153/bolt-pistol-replica-warhammer-40k-prop

https://www.thisiswhyimbroke.com/space-marine-costume/

https://technabob.com/blog/2013/05/18/warhammer-40k-blood-angels-costume/

http://mytpb.com/cosplay-thursday-space-wolf/

And the heavy bolters are worse, with bean can sized bores on the muzzles.

There's no way you can justify such oversized bores with the way bolts work. Unless the bolter barrel stops inside the casing and that thing is just a flash suppressor, but I don't think so given how short the barrel already is...



I've got no problem with big and chunky guns for marines per se. IMO as they are heavily armoured they need armoured weapons. Especially as they carry their bolter across their chest. The kind of incoming fire they would get means they could easily lose function in their gun from shots aimed centre mass.

So my perception is that the bolter you see marines carrying is basically shrouded in an armoured case. It's the armour that makes it heavier, not being a 'marine' version (one of the few things I really hated in the ffg RPG). An imperial guard bolter would just remove the shroud, but it would still be the same gun.

 Flinty wrote:
A rocket round would be longer though as the proportion of propellant in the casing is reduced to basically enough to.get it out of the barrel.with the rocket kicking in after that. Also I recall bolt rounds being mass reactive rather than impact armed, so.that would probably help with miniaturisation

I basically assume that the casing on a boltgun round is actually the rocket motor and is pushed out attached to the "bullet" rather than burning in the chamber, since you only need a small boost charge to get the round out of the barrel. Picture:

Yeah, but there's a ton of other elements that would need to be present. a venturi for the rocket motor, some sort of spin stabilisation system (although this can be done using diagonally offset venturi to impart spin) plus, a rocket motor needs some length to actually burn down. a stubby little chunk of rocket propellant like that will just deflagrate in a burst of flame. And then on the actual projectile, you'd need a hardened penetrator to get through any armour (definitely not enough room for a shaped charge as well as all that) and some sort of delay PIBD initiation system for the explosive charge.

also, you've got to consider the practicality of having rocket propelled rounds. we already have propellant rounds that are more than capable of taking projectiles across huge distances. generally, the combat in 40k takes place in much closer range. rocket rounds are totally unnecessary.

It's not as crazy as it sounds. The gyrojet shot rocket-propelled rounds that were around .50 caliber. It had issues with accuracy and manufacturing the ammo was a headache, but it actually worked.

A bolt would simply be a bigger, much more sophisticated version of this. It's about as realistic as a lasgun power pack containing enough energy to shoot (a few dozen times) a laser powerful enough to kill someone...

In my humble opinion:
I think the bolter is a hybrid gyrojet/ballistic weapon that in human sized calibres is approximately 12-14mm and in astartes pattern(which is what I will continue to talk about) perhaps 20mm while the heavy bolter and perhaps bolt rifles of the primaris marines would be approximately 25mm(it is heavy afterall).

Although the bolt rifle maybe a 25mm necked down to 20mm. Velocity gained through traditional ballistics would be more suitable for close quarters penetration against armour, while the rocket would provide a much longer effective range against armoured foe (ie astartes). This would explain the extended range.

I think for it to work it would not look like it is displayed, this round is much too short and has no advantages from being so stubby. This would indicate this weapon is a glorified grenade launcher, and a poor one at that.

Basically a long projectile is stable (and has more room for rocket fuel and thus velocity) and more powder behind that means you have a higher velocity leaving the barrel of the weapon. So more AP up close.

A fat round is only good for explosive payload. At this point you want to look at their idea for penetrating armour, as this weapon seems to be designed (in my eyes at least) specifically for killing armoured astartes (penetrating their ceraminte power armour and blowing them apart and therefore bypassing their traditional hardiness). And I guess when you got a weapon designed to do that, well it works against most things.

The traditional fat blunt round is not promising here. Might be concealing a HEAT tip. Although not big enough for a tandem warhead(which depending on how their armour and black carapace works may actually be critical, it has occured their big bulky armour maybe a similar spaced armour shell as you see on the Challenger and Abrams). Although I read something about something depleted being put in the tip. Uranium I guess is their inspiration, and that is no shape for a kinetic penetrator.

At least this is what it wants to be.

Sadly very clearly it can not be such an effective weapon, because every guard unit has acsess to a lot of heavy bolters, and they seem to perform insignificantly greater than a M2 browning or have much more AP power than fragementation from a 40mm frag grenade. In other words it can puncture up to like 25-30mm of RHA which is pitiful. So basically it's a marine carried 14.5-15mm carbine, flying at pitiful speeds, skinned as something else more exotic.

Basically to be what it indicates it wants to be (by fluff description) it needs to ignore feel no pain saves (ie you might be a tough pipe hitter and all but I just blew your arms off,(or a melon sized hole in your torso(I'm talking big ass watermelon, none of those pussy honey dew or rock melon sorts here)) you are by definition combat ineffective) It needs to really hurt light vehicles. It needs to do 2 wounds and slaughter guard equivalents in the biggest case of over kill ever. In the hands of an astartes it should reach across the board with a range usually reserved for high velocity tank cannons and with a terrible accuracy.

The game rules are an abstraction. The bolter has more strength and better anti armour capability than a normal ballistic rifle (I.e. the autogun) this is an abstraction of the extra possibility of killing the target through a direct hit causing catastrophic internal damage, or from near misses triggering the mass reactive charge and peppering shrapnel into the target. Heavy bolters again have a step up in strength and AP based on higher rate of fire and larger projectiles, I.e. a burst of fire from a heavy bolter is more likely to be effective than one form an ordinary bolter.

One dice roll does not necessarily indicate a single round fired.

see you say that, but what does mass reactive even mean? most people seem to think it means that the secondary explosive charge will detonate after penetration into a significantly solid object, eg a space marine with his armour and huge bulk. this in itself would require some sort of detection system or device.

what you say seems to suggest some sort of proximity sensor, which would be even more complicated to get into a shell.

In 40k terms, "mass-reactive" merely means that it has a split-second fuse before it explodes so it explodes an instant after impact and penetration instead of on impact. The idea being it penetrates then explodes for maximum damage.

I remind you, though, that it still really doesn't matter how impossible it would be to do this with modern technology.