Thaddux said:

yeah the set values are a bit iffy, at the top of my head I think multiplying the weapons clip value with each weapon you pick works better.

As for the hot-shot lasgun, one can assume it basicly has a built in backpack "clip" in it´s stats, so it´s always 30 shots, because you´re already wearing a backpack "clip" by default with that one. Also remeber hot-shot Lasguns aren´t stitched to a Stormtrooper, one can assume in missions where ammo scarecity is expected they leave the hot-shot at base and bring a normal lasgun, there´s a reason all players get the items from the regiment kit.

No one in their right mind would spend resources on an expensive weapon that can't even be used in any kind of extended battle. Especially when you expect the soldier carrying that weapon can be expected to fight behind enemy lines, without resupply. "Just leave the gun at home" is a poor argument.

DJSunhammer said:

well here is a classic case where war game and rpg translation gets iffy, in the war game, Stormtroopers are basicly heavy armoured frontline fighters, where ya can argue fluff wise they have some guardsman acting as there ammo monkey fetching new backpacks from base. Of course one could house rule and give them ammo as the backpack "clip". I personally think the hot-shot is intended to be the Stormtroopers frontline gun (and it makes sense, with few expeptions a Stormtrooper player is more likely to get frontline duty then the spec ops work lore say they do) and the trooper wisely picks something else for those spec ops missions.

remmus said:

CaptainTrek said:

The standard armament of the grenadier squads is the XIV Lasgun (heavy), referred to by troops as the Hellgun, or more rarely 'hotshot' lasgun. In effect this is and overpowered lasgun, firing in the 28 megathule range and incorporating many additional features. The weapons powerpack is worn as a backpack, and the power cables run to the weapon's rapid discharge generator, which forms the weapon's main mechanism, where energy for each shot is stored. The heavy powerpack supplies enough power to keep the weapon firing for two hundred shots, depending upon the power setting and the weapon's condition.

Imperial Armour Volume 5 - The Siege of Vraks, page 88

I've looked around and that is the only source I've managed to find on the ammo capacity of Hellguns/Hotshot Lasguns.

Emperor Castaigne said:

Any indication of whether that kind of backpack would be like the lighter 10kg one or the heavier 25kg one?

Well, even if we assume the 25kg one, that's still 2.5 times the number of shots it can hold by OW or (errated) Rogue Trader RAW, so perhaps we could say the 25kg one holds 200 shots, and also increase the number of shots the lighter 10kg pack can hold by 2.5 times, resulting in it being able to carry 75 shots. That seems relatively reasonable to me…

If 'thule' is a Gothic form of joule, then the calculation is probably in megajoules per second. 28 is a LOT [just under 8kW hours] but we could be looking at a series of pulses [Lasguns causing explosions generally implies a subsequent pulse expending its energy into materials sublimated by a previous strike in a very short span of time] amounting to a fraction of a second. Even a quarter second like this, though would be roughly equivalent to concentrating a speeding pickup's impact into a very tiny area. Still, Lasers are fairly inefficient, its just that electrical power is one of those things we've really learned to convert anything into, and so its extremely plentiful..

Not taking into account the fact that 1d10+4 two-shots a normal human about half the time if you're not too unlucky [at that much energy, you'd need a lot of luck to survive just one] unless the weapon is really, really bad at transfering its energy [which given the explosions it causes, it is] and so is rather weak [it certainly fails against daemons since they mostly use TB and not AP], you're still looking at very little ammunition there. Those 16kg would be much better spent on a Long-Las with three spare charge-packs and TWENTY Krak and Frag missiles.

Speaking of missiles… Usually the missiles are much heavier and the launch unit a good deal lighter. Even the rather heavy, and anti-air [I somehow doubt there's much of a guidance unit involved in the regular guardsman krak launcher…]  Stinger launcher is just 15kg, a very far cry from a 300m ranged RPG-launcher.

Yeah, I did the calculations once for another RPG. Any battery capable of giving you a lethal (let alone effective against armour) directed energy weapon good for more than a few shots is packing enough juice to run an electric car for multiple laps coast-to-coast across the US.

Your standard OW trooper is carrying around a terrifying amount of power.

And if the Imperium didn't suck at technology they could use those batteries to run rail guns instead of lasers and give the average infantry soldier a weapon capable of pithing a baneblade. Oh well.

Except they couldn't… Any weapon capable of punching through inches thick armor is going to have enough recoil to turn a human being into paste when he fires it. Not a very useful weapon to be honest.

DJSunhammer said:

last I checked recoil is caused by the rapid expansion of gas when the powder in a current day bullet explodes, rail & gauss weapons is about using magnetism, directing all the force forward along the barrel (unlike a bullet, where the gas is leaked both front and back, the later the cause of recoil)

Not quite:

First, you have to remember that this is total energy, and not all of it goes directly back into the person firing it. Some is instead lost as heat, light, vibration, some is even reflected back and partially granted to the outgoing projectile. In addition, the amount of energy it takes to accelerate, say, a one pound slug at those velocities is small compared to what would be needed to accelerate the weapon firing it [if the weapon is even just ten pounds, it would gain a fraction of the momentum imparted to the projectile].

The 'equal and opposite reaction' is not a direct "the gun must move backwards" effect unless you're a hollywood movie writer. Even in regular guns, only a small portion of the total energy produced goes into producing recoil.

A hand-held rail weapon is likely several kilograms, yet is accelerating just a few grams of metal at a time. As it uses a directed force to eject the projectile instead of a contained explosion, it is also easier to predict and compensate for atop all that. Given its propelled by effects of the Lorentz Force, you could even argue that the weapon is specifically designed to transform electricity into recoil; said recoil being what fires your little metal dart.

The tthree main problems with rail guns is that, due to Newton's First Law they would have monstruous recoil that would require extremely powerful compensation, that the energy required to accelerate any object larger than a subatomic particle is colossal, and that the magnetic forces that accelerate the slug put the rails under steel-bending stress. How the Tau figured out how to solve these problems is anybody's guess.

remmus said:

Recoil is caused because, in essence, you are moving something at very high speeds. In order to move even a small piece of metal like a bullet, you need something to push off of. This is true for both conventional firearms and for magnetic weapons like rail and coilguns. If you push a projectile in one direction there will be an exact copy of that force pushing in the opposite direction. Any heat created by a railgun is going to be caused by two things. Friction and electrical resistance.

@ Kiton:

Yes, quite.

To put it simply. For every action there is an equal and opposite reaction. Always. There are no exceptions. All of the force used to push even a small chunk of metal is also going to be pushed into the weapon that fired it, and the person holding that weapon.

If, even in normal guns, only a small portion of the energy produced goes into producing recoil the opposite is also true. Only a small portion of the energy produced goes into pushing the bullet out of the barrel.

That last part of what you said makes no sense at all. Recoil is reactionary force caused by firing a gun. It perfectly balanced in relation to the forward momentum of the projectile and anything used to fire it. You cannot fire something with recoil. Nor does trying to rewriting the definition of recoil make that last statement anything less than true.

@JuankiMan: You mean Newton's Third Law, not his first.

JuankiMan said:

You know we have rail guns now right? It's just they are bulky as heck because we do not have access to 40k batteries. Also capacitors.

In any event if you want to hurt someone with a given amount of energy, you will get much more bang for your buck if you use that energy to propel a slug (or arrow, or shiruken) than you will by turning it into radiant energy and giving them a tan. Sure, you can hurt someone with a kilowatt laser, but unless they are unconsious or tied up it's only going to be painful but not incapacitating surface burns. To hurt someone quickly you need a LOT of energy in that beam.

Plus with a slug thrower you can take advanatge of useful material properties in your ammo types. For example titanium cores or depleted uranium (who are we kidding? The Imperium would use enriched uranium for better damage, they weren't planning on paying those guardsmen retirement anyway) to help you punch through the armour on a tank.

You know, when I wrote that post, I considered if I should exclude the part about "28 megathule" due to the threat posed by a physics debate derail, but I ultimately decided to copy over the entire piece for context.

I am unsurprised that it did take this turn.