Hi All

So our group have recently started with Dark Heresy 2nd ed and overall like how it's changed from 1st ed particularly when it comes to ammo. I remember my first Dark Heresy character measured his wealth by how many bolt gun shells he had.

When Rouge Trader came along and streamlined ammo supply away from counting the pennies and book keeping we were overjoyed. Now we have 2nd ed which is a hybrid of this (and I can see why to an extent) with using influence and being able get get more with a good roll.

We have now that standard ammo is one availability easier to obtain than the weapon, eg Autogun is average so the ammo is common.

So taking all this into account my character, a wannabe Inquisitor, have got my hands on a Purgatus Crossbow (Rare), the standard ammo for this going by the main rules should be Scarce. Therefore what is the crossbows standard ammo, from the description we have:

The Purgatus can use any type of shotgun and crossbow
ammunition, as well as its own Purgatus Stakes (see page 47).

Looking at this description then the Purgatus Stakes are the crossbows standard ammo just like needles are the standard ammo of the needler. Yet the stakes have their own entry that has an availability of Extremely Rare, two steps harder to get than the only weapon that can use them, this seems rather odd to me.

If the stakes aren't the standard ammo then what is, are we looking at a standard shotgun sell or crossbow bolt? Each of these would have a availability of scarce with a weight of 0.3 kg per round. Yet a shotgun ammo has an availability of Common with a weight of 0.06kg, 5 times less weight.

This then brings us to some more oddities regarding ammo, the Backpack Ammo Supply. This adds 15kg to the weapon yet if we look at the way it works we can see that this 15kg breaks down.

As can be seen the Heavy Bolter is doing some king of weight compression managing to get 20kg of ammo to fit into 15kg of backpack excluding the backpack own weight.

Also a backpack for the combat shotgun holds over twice the ammo than a normal shotgun yet they have he same ammo.

We can also see that the Purgatus crossbow has the heaviest ammo even beating the heavy bolter.

Finally if the weapon has a backpack ammo supply do we have to acquire 5 clips of ammo to fill this up.

(edited for table)

If the stakes aren't the standard ammo then what is, are we looking at a standard shotgun sell or crossbow bolt? Each of these would have a availability of scarce with a weight of 0.3 kg per round. Yet a shotgun ammo has an availability of Common with a weight of 0.06kg, 5 times less weight.

"Standard" is relative. Weapons that can fire different types of ammunition may see different people and organisations use different rounds as standard. For example, the tabletop codices once mentioned how Guardsmen and Marine Scouts use the same shotgun, yet the Imperial Guard issues its troops with fragmentation rounds, whereas the Astartes use solid slugs by default.

In this context, I think it would make most sense if you simply regard all choices of ammunition as Special Ammo for the purposes of determining availability, since neither the stakes nor the bolts and shotgun shells are dependent on the availability of the weapon you are going to fire them with.

Simply put: if all types of ammunition are listed with their own availability, then you're going to use that. Seems pretty clear!

As for ammo weights, I would not think too much about it. The numbers are pretty much guesstimated anyways. What's more, as far as I remember the ammo weights are dependent on the weight of the gun, which gets funny once you notice how some rounds can be used with weapons of vastly different weights.

If you don't like the RAW here, just houserule it. For the backpack weapon supply, I'd simply say that it adds a basic amount of weight to account for its own mass (3-5 kg?), and then provides a certain amount of space that can be filled up with ammo up until you reach the total weight capacity. In short, the backpack's advantage should not be to lower the ammo weight (quite the contrary, it should overall be heavier!), but that you do not have to reload and that you can carry so many rounds easily accessible in the first place.

Finally if the weapon has a backpack ammo supply do we have to acquire 5 clips of ammo to fill this up.

Yes -- if you only use the rounds from one clip it'll only be 1/5 filled.

For ease of use I'd just re-calculate refill cost and weight on the sheet for this one, though, as it seems unlikely you'd ever need/buy single clips ever again, unless you have another weapon that uses the same ammo.

Good analysis. To nitpick, the Hot-Shot Lasgun always uses an ammo backpack in the first place, so adding another ammo backpack would require another person to carry it.

Ammo weight and rarity gets weird with those weapons that share ammunition types. In case of weight, a larger or more complex clip/magazine may be involved for larger/higher capacity weapons, but this can only go so far.

What I'm seeing in the backpack math is that it's most beneficial for Heavy weapons and weapons with long reload times. In some cases the feed mechanism is likely adding weight, in other cases the backpack's design is better enabling you to carry the actual weight at a lower listed weight (best explanation I could ass-pull).

Good analysis. To nitpick, the Hot-Shot Lasgun always uses an ammo backpack in the first place, so adding another ammo backpack would require another person to carry it.

Ammo weight and rarity gets weird with those weapons that share ammunition types. In case of weight, a larger or more complex clip/magazine may be involved for larger/higher capacity weapons, but this can only go so far.

What I'm seeing in the backpack math is that it's most beneficial for Heavy weapons and weapons with long reload times. In some cases the feed mechanism is likely adding weight, in other cases the backpack's design is better enabling you to carry the actual weight at a lower listed weight (best explanation I could ass-pull).

You are incorrect about the hot shot las weapons. While they do say that they have 10kg power packs it then specifically mentions that these can be upgraded to larger packs for more ammo and it then links the backpack ammo page.

The backpack ammo supply's rules are definitely odd. I much preferred the rules from Rogue Trader where it just listed a specific amount of ammo based on weapon type. So SP weapons got 200 ammo from it while a las weapon got 80. Not perfect but at least it makes solid projectile and bolt weapons make a little more sense. Energy weapons can still be wonky though (las pistol gets as many shots as lasgun and as lascannon) but I still prefer it.

For the purgatus crossbow I would say it's basic ammo is scarce availability bolts(one step down from its availability) that give it the profile it has with no additional rules. All other ammo types are special ammunition and are their listed availability. Why would you even want to use the purgatus crossbow bolts? The silver stakes are easier to get and in my opinion much better. Both are sanctified, the psychic phenomenon is just as likely to do nothing or screw over the party as it is to harm the target especially in the case of a daemon and they get a test to resist it, while the silver stakes just cause extra damage with no risk or downside or chance of having no effect.

My group doesn't pay close attention to the weights for equipment and ammo. Its a lot of extra book keeping and some of the numbers seem pretty off anyway. We just vaguely try to keep things reasonable as to how much we can carry in terms of bulk. Probably only going to carry a few spare clips unless you can justify to the GM where you're putting any others. If we aren't wearing a set of armor but are bringing it with us we have to justify how we are carting it around. Any extra gear we store in some sort of safe house.

10kg power packs [...] upgraded to larger packs for more ammo

That just doesn't sound right.

The backpack ammo supply's rules are definitely odd. I much preferred the rules from Rogue Trader where it just listed a specific amount of ammo based on weapon type. So SP weapons got 200 ammo from it while a las weapon got 80. Not perfect but at least it makes solid projectile and bolt weapons make a little more sense. Energy weapons can still be wonky though (las pistol gets as many shots as lasgun and as lascannon) but I still prefer it.

Hmm. How about a simple formula that includes stuff like, say, dividing ammo for Heavy weapons by 2 or 3?

That being said, I think it would actually be possible to create a short table with how much ammo the pack could hold for specific weapon types ("SP Pistol", "E Basic", etc). It'd lump some of them like plasma guns and lasguns into a single group, but overall it could still feel more consistent.

Looking at this description then the Purgatus Stakes are the crossbows standard ammo just like needles are the standard ammo of the needler. Yet the stakes have their own entry that has an availability of Extremely Rare, two steps harder to get than the only weapon that can use them, this seems rather odd to me.

If the stakes aren't the standard ammo then what is, are we looking at a standard shotgun sell or crossbow bolt? Each of these would have a availability of scarce with a weight of 0.3 kg per round. Yet a shotgun ammo has an availability of Common with a weight of 0.06kg, 5 times less weight.

The Purgatus Stakes are not the standard ammo. They are a special ammo, that only can be used in Purgatus Crossbow, that adds effects on top of the statline given in the weapon table.

The standard ammo, which only has the base stats, would be scarce. I'm guessing it's just a simple crossbow bolt made of solid wood and/or metal. It would give you the statline in the weapon table.

Or you could grab any special ammo that could go into a crossbow or a shotgun. The interesting bit is that there is special ammo the Purgatus Crossbow can use which is scarce, so you probably won't have any reason to go with standard ammo unless you're having to craft it yourself.

That's not really surprising. I'd expect crossbow bolts to be heavier than most bullets in real life.

Think about how many different bullet sizes we have in real life. Even if you're just talking pistols. Different guns having different ammo weights isn't a surprise. Though a comparison to real life ammo weights could prove interesting.