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Durloth
03-04-2009, 17:57
I`m making a diorama with a Forge World heavy bolter and a termie with a stormbolter. The heavy bolter come a holes in the barrel, but not the storm bolter. How wide shuld I make the holes in the barrel of the storm bolter compared to the heavy bolter?

Wolflord Havoc
03-04-2009, 18:02
As far as I am aware the 'Standard' (S4 AP5) Bolter round is .75 Cal (19.05mm) while the heavy Bolter round is larger at 1.00 Cal (25.4 mm) - so as a rule of thumb I would make the Storm Bolter Barrel about the same diameter as the holes on the side of the bolter barrels muzzle flash-hider (IIRC a 2.1 mm drill is the right size).

Gorbad Ironclaw
03-04-2009, 18:04
I thought bolter rounds was 0.50 Cal?

Durloth
03-04-2009, 18:13
@Wolflord: I`m a fantasy-guy, so sorry for my ignorance, but are a storm bolter the same calibre as a regular bolter?

Edit: thanks for your replies.

sliganian
03-04-2009, 18:19
I thought bolter rounds was 0.50 Cal?

Well, Bolters are SUPPOSED to be minuature rockets. If anyone remembers the RPG 'Star Frontiers', bolters would be gyrojets (less the minimum range requirement)

However....then the 'artists' at GW got a hold of them. Suddenly all bolters start kicking casings out the side like a 9-mm. :mad:

So I don't think there is a precise calibre because GW can't keep its own story straight.

Tarquinn
03-04-2009, 18:22
Well, Bolters are SUPPOSED to be minuature rockets. If anyone remembers the RPG 'Star Frontiers', bolters would be gyrojets (less the minimum range requirement)
.

You don't have to remember a RPG for Gyrojet firearms (http://en.wikipedia.org/wiki/Gyrojet).

Lord Humongous
03-04-2009, 18:56
Given that storm bolters have the exact same STR and AP as a bolter, I'd say its the same caliber, even the same ammo (as shown by stermgaurd). Fluff wise, the storm bolter is a refinement (mostly in the feed mechanism) of the twin linked bolters that chaos still uses. The chaos twin linked bolter is literally made from two bolters side by side, so it OBVIOUSLY uses the same round.

That said, GW does not seem very consistent with the barrel sizes on bolters and especially on twin linked / storm bolters. Even less so when you compare one race vs another, or pintel versions vs man carried.

FWIW, bolters ejecting shells makes SOME sense. IIRC, the idea is that they are kinda like grenade launchers (low chamber pressure, low round velocity, large caliber) with the grenade actually being a mini-rocket (to extend the range a bit). Makes zero sense for a pistol (or really any other use), but that's the fluff.

Bunnahabhain
03-04-2009, 19:18
Storm bolter calibre should be the same as your standard bolters.

Now if only you can find bolters from multiple ranges with the same barrel, then you're laughing.

MajorWesJanson
03-04-2009, 20:07
Marine pattern weapons are .75 caliber, while the .50 caliber bolters are probably guard/human issue. Heavy Bolters are 1.00 caliber, and are marine-portable or tripod mounted for humans.


Now if only you can find bolters from multiple ranges with the same barrel, then you're laughing.

Different amounts of propellant.

As to the shells, bolter rounds may be dual stage, with an initial charge like modern bullets to give it a fast initial velocity, and the gyrojet system to keep it stable and high velocity over range.

sliganian
03-04-2009, 20:10
You don't have to remember a RPG for Gyrojet firearms (http://en.wikipedia.org/wiki/Gyrojet).

Cool! Thanks for that link. :D

Cue the "The More You Know" rainbow.

Isambard
03-04-2009, 20:13
This might help:

http://takentooseriously.blogspot.com/2006/09/secret-lives-of-bolters.html

borithan
03-04-2009, 23:39
Well, Bolters are SUPPOSED to be minuature rockets. If anyone remembers the RPG 'Star Frontiers', bolters would be gyrojets (less the minimum range requirement)

However....then the 'artists' at GW got a hold of them. Suddenly all bolters start kicking casings out the side like a 9-mm. :mad:The idea of cases doesn't make no sense. The bolter fires the round like a low velocity, high caliber rifle, and then as the bolt leaves the barrel the rocket engine kicks in. The first stage does not have to be done with caseless ammunition.



Marine pattern weapons are .75 caliber, while the .50 caliber bolters are probably guard/human issue.Dark Heresy suggests that .75 is the size of standard sized bolters, while Space Marine ones are larger (whether longer or wider I don't know, but they have the same damage as a standard heavy bolter round). Now, myself, I don't like this, preferring to think that Space Marine bolt rounds and normal ones are identical, just Space Marine bolters are properly sized for themselves (as in bulky... not bigger bullets), and have extra dinky features that normal bolters don't like fully automatic and burst settings, while, from what I have seen in multiple sources, normal bolters are semiautomatic.



with an initial charge like modern bullets to give it a fast initial velocityNot a great deal of sense to that. The only real reason for producing a self propelled round in a small arm would be so that it could fire a large round with less recoil than would be expected for such a size, so would probably fire it at an initial low velocity.

Born Again
03-04-2009, 23:45
As to the shells, bolter rounds may be dual stage, with an initial charge like modern bullets to give it a fast initial velocity, and the gyrojet system to keep it stable and high velocity over range.

As far as I'm aware, this is correct. Back when I got into the game in 2nd ed, I believe it was always stated that bolters used cased ammo, with the rocket igniting once clear of the barrel. I'm not sure exactly where the retcon they were caseless comes from as I spent a few years away from the game.

silentsmoke
03-04-2009, 23:48
Could it be .75 cal....BAM!!

R Man
03-04-2009, 23:57
I always thought that the gyrojet aspect of the shot was to reduce re-coil rather than the primary means of propulsion.

And don't most assault rifles these days have variable settings of Safety, semi-automatic and automatic? So in most circumstances soldiers would use semi to reduce ammunition waste, but if you had a wave of orcs then switching to automatic might be an idea.

Col. Tartleton
04-04-2009, 00:21
Marines with safeties... lol.

Somehow that's going to bite them in the anus.

"DIE TRAITOR!!!"

*Click*

"Ho $#!% its on safety!"

*Punch With Power Fist*

"ASTARTE DOWN! ASTARTE DOWN! AURRGH..."

Wolflord Havoc
04-04-2009, 01:05
Marines with Safty catches - Brilliant

Marine wiggles is trigger finger in your face

"Thats my safety catch!"

Mind you if they did have safety catches then I am sure that by the time said marine was in a firing line about to shoot some orks his muscle memory for the function of shooting the weapon would have been so ingrained that it would be as natural as breathing.

According to the Ranger Handbook it takes 2500 (IIRC) repeats of a process before it becomes natural.

I would suspect that said Marine would be as likely to forget that his safety catch was on as I would have of farting my way to Mars.

Lyinar
04-04-2009, 02:01
Bolters are of varying calibres. I tend to see the Marine bolters as the .75 calibre ones, while the ones normal humans get (and most bolt pistols) are probably .50 calibre to allow for them to be able to carry close to the same amount of ammunition that the Marines do with their hulking monstrosities. And really, given the mechanics of bolter ammo, there isn't going to be that much of difference in terminal ballistics between .50 cal and .75 cal on a normal person anyway.

My impression is that the ones in the pictures ejecting the shell-casings are fired by a traditional firing pin slamming into a traditional primer and igniting a very small charge that imparts enough velocity to the round for it to be lethal at point-blank range, and generate enough recoil to cycle the action of the weapon, while the rocket provides the majority of the round's propulsion and ignites just past halfway down the barrel (to provide much-needed in-flight stability).

Why would it be so complicated? Simple. There were two major problems that the Gyrojet system had: that lower-quality ammunition would be wildly inaccurate as it spun out of control from the rocket exhaust ports not being perfect, and that Bugs Bunny's old trick would actually work. The muzzle velocity on a Gyrojet was low enough that you could literally stick your finger in the barrel and the round would never make it out. Fifty yards downrange and it was more than adequately lethal, but the unique flight profile of a rocket-propelled small-arms projectile meant that it started out very slow and kept accelerating until the motor ran out of fuel (whereas normal bullets tend to hit their maximum velocities just before or just after they leave the barrel, depending on the amount of powder behind them and the length of the barrel).

borithan
04-04-2009, 08:11
As far as I'm aware, this is correct. Back when I got into the game in 2nd ed, I believe it was always stated that bolters used cased ammo, with the rocket igniting once clear of the barrel. I'm not sure exactly where the retcon they were caseless comes from as I spent a few years away from the game.As far as I know it was never said that they were caseless (and still isn't), but the oldest artwork, that on the front of the Rogue Trader rule book has no cases being ejected, just gas coming out of some port in the side, and many of the RT era pictures of bolters don't look like they have an ejection port (again, just some gas release area). However, quite quickly they started showing bolters being fired with cases being ejected out of the side. Now, initially this may have been a gaffe by some artists, but it is now clear that Bolters are usually considered to use cased ammunition.

StormWulfen
04-04-2009, 08:18
bolters are.75 cal, it says on the ammo crate i got with my rulebook;)

Born Again
04-04-2009, 13:38
As far as I know it was never said that they were caseless (and still isn't), but the oldest artwork, that on the front of the Rogue Trader rule book has no cases being ejected, just gas coming out of some port in the side, and many of the RT era pictures of bolters don't look like they have an ejection port (again, just some gas release area). However, quite quickly they started showing bolters being fired with cases being ejected out of the side. Now, initially this may have been a gaffe by some artists, but it is now clear that Bolters are usually considered to use cased ammunition.

Awesome, glad someone can clear that up for me. I know the RT picture and you're right. I never paid attention to that though. Regardless I've never seen canon text stating them to be caseless, and most models have some form of ejection port so I'm going to assume most are using cased ammo, though there may well be caseless versions in use somewhere.

Hellebore
04-04-2009, 13:43
Well an ejection port isn't completely evidential for cased ammunition, even caseless ammo needs one in the case of jams.

However as far as I know they are cased ammunition.They are mentioned as being fired out of the barrel at 'low velocity' BEFORE their propellant kicks in, in the 2nd ed Wargear book, so if they were ever referred to as caseless then it would be printed before that.

Hellebore

AndrewGPaul
04-04-2009, 13:55
Hellebore, I don't see how that description rules out them being caseless.

Rogue Trader doesn't even make mention of them being gyrojet rounds - that must have come later. Possibly in Confrontation or the Battle Manual.

Hellebore
04-04-2009, 13:59
Woops, I got my points crossed. I was thinking of the conventional propellant IN a case, not the case itself.

You are right of course, the shot could be put out without a case in that manner, because caseless ammo is stuck inside a block of propellant.

As yet I've not found anything referring to them as caseless or cased for that matter.

Hellebore

Born Again
05-04-2009, 13:12
Hence the reason I think there's probably different models from different forgeworlds, making cased and caseless versions.

We do know however they definitely use propellant of some kind other than the gyrojet, which is implicitly stated as igniting once out of the gun.

Bregalad
05-04-2009, 13:15
Look at the Leman Russ tank turret and don't bother with correct calibres in 40k any more ;)

SimonL
05-04-2009, 13:43
Look at the Leman Russ tank turret and don't bother with correct calibres in 40k any more ;)

We have a winner! :D