"This is like the type of post I would make when I accidentally take too much of my ADHD medication." -- /u/goobushoobus
"Actual tears forming right now, just thinking about the time spent on this that could have been used for something - literally anything - worthwhile." --/u/EssarD
(Note: I originally wrote this series on Reddit. This post has been very slightly edited.)
Lasguns. Derisively called flashlights, blinkidoodles, and laser pointers (ed. note: one of those may be made up) by fans, these are unquestionably the weakest standard-issue weapon of any of the commonly-playable 40k factions, regardless of edition. As a result, I can't even begin to count the number of times I've heard someone ask why "everybody doesn't just have a boltgun? They're clearly better in every way."
I've seen answers to this question rely on weight or recoil, claiming that a boltgun is too heavy for an unaugmented human... and yet, they've been wargear available to Guard sergeants or characters for decades. The signature weapon of the commissar is a bolt pistol, so bolt weapons generally are clearly not outright dismiss-able for this reason. I think this is a valid argument, but not an airtight one.
I've also seen answers that say that boltguns are simply too expensive or complex to issue in the numbers required for the Imperial Guard, which numbers trillions across the galaxy. This gets a little murkier, as the economics of how the Imperium equips its troops is both complex and vague. I also think this is a valid argument--they ARE too expensive to issue en masse--but proving it is much harder, as any such proof relies on numbers (prices of boltguns or rounds, tax revenue from various worlds) given to us by Games Workshop, and these numbers tend to be inconsistent and rare.
So let's put all that aside. Let's pretend the Imperium has both infinite wealth and production capacity, and can manufacture unlimited lasguns, autoguns, and boltguns (and the ammo for these weapons) with ease. Even if this were true, I'll show you why the lasgun is not only the best, but in fact the only option for the Imperial Guard. That reason is due to the weight of ammunition. (note: I threw Autoguns in there as a comparison of why lasguns are considered superior to autoguns in the books, even though they usually have identical game stats).
How Much Ammo Does a Guardsman Use?
To answer this question, we'll ask the Pentagon. Creating accurate estimates of ammo consumption is actually critical for modern industrial warfare, so this is well-trod territory. I'll turn to data from World War Two not because it is the closest analogue to 41st millennium warfare, but because it is extremely well-studied and it happened long enough ago that all the docs are declassified. We'll use the "Day of Supply" column on page 736 of Global Logistics and Strategy 1940-1943 as our guide. A "Day of Supply" was an estimate of how much ammunition, on average, one user of the listed weapon would require per given day. Obviously not all days are equal, but over months and years the "storming of Normandy" is balanced out by "umpteen days marching from place to place."
Obviously, the Pentagon doesn't have data on autoguns, lasguns, and boltguns, so we'll pick a close analogue for each. Let's assume that an unaugmented human primarily fires boltguns in semiautomatic configuration, under the assumption that full auto would be too much recoil for a regular human to handle. Let's thus place the ammo consumption of a guardsman with boltgun as equal to a WW2 .30 cal semiautomatic rifle, that being 5 rounds per day. This assumption holds true even though a boltgun is much more powerful than a .30 rifle: in WW2, anything hit squarely with a .30 rifle can be expected to stay down. This is true as well in the 41st millenium.
Let's assume that both lasguns and autoguns, being select-fire weapons (and thus, not directly represented in the data, as this type of weapon was not used by the US during WW2), fire 50% of the time in single-shot mode (equal to a .30cal rifle) and 50% of the time in full auto (thus equal to a .45 submachine gun) for 2.5+10=12.5/day. (Side note: a boltgun in the hands of an astartes, which will sometimes make use of full auto mode, will have the same ammo consumption) To avoid the impression of this being a precise number, values per year will be rounded to the nearest hundred units.
rounds per day per month per year
Lasgun: 12.5 375 4600
Autogun: 12.5 375 4600
Boltgun: 5 150 1800
And How Much Does That All Weigh?
Let's place the weight of an autogun round as equal to a modern 5.56mm assault rifle round: 12.31g per round. Easy enough.
A standard godwyn-pattern Astartes boltgun fires 0.75 cal ammunition. (in some places this is cited as .998; let's assume that a human-scale boltgun uses the smaller of these two calibres). This is huge, and estimating its weight is difficult. I'm sure that this-or-that sourcebook will tell us its actual weight, but given GW's flexible arrangement with technical numbers, I'll determine an approximate weight for it myself from base principles. A real-world .50 cal cartridge (fired by a 40k Heavy Stubber) varies by type, but weighs around 114g per round. These are considered very large bullets, at the very upper end of what can be fired by a weapon held by a human being. A .75 calibre round has an area of 2.25x that of a 0.50cal round. If we assume the length is the same as a .50cal (because bolt rounds are often shown being quite wide and fat compared to other types of bullets), then each has a weight of 256.5g. Obviously there's a pretty huge margin of error for this number, but I have to use something, so let's go with this for now.
Lasguns don't shoot bullets, but rather, they use rechargeable power cells. These are generally used in Black Library books as being pretty well interchangeable with regular rifle magazines, so we'll say (arbitrarily) that each one weighs as much as a fully-loaded M16 magazine: 480g. You'll find I'm not too fussed about this weight, because pretty much any number you can put in there will result in the same conclusions.
Because these cells can be recharged indefinitely, there is no need for a constant supply of ammunition as with projectile weapons. Thus, however much ammunition a soldier might need in a single battle is all that is needed for an entire campaign. An American infantryman carries 7 magazines of 30 (one loaded, and six on their bodies) for a total of 210 rounds. Let's say that, in order to account for occasional periods of heavy fighting without a break to recharge the power packs (such as a single major assault), that double this number is alloted to each guardsman, or 420 rounds per guardsman.
According to Imperial Munitorum Manual by Graham McNeill, pgs. 61-62, a lasgun power cell holds enough for ONE HUNDRED AND FIFTY SHOTS. Thus, three power cells (1.44kg) of power cell is all that's needed for the lifetime of an imperial guardsman. Thus the supply train (for ammunition) for lasguns is functionally zero, barring the occasional replacement from wear and tear (but no more or less than replacing any particular equipment).
With these numbers, we can produce this table of weight of ammunition used per described time increment:
weight (kg) per day per month per year
Lasgun: [1.44kg--------------------------------]
Autogun: 0.15kg 4.61kg 56.14kg
Boltgun: 1.28kg 38.475kg 468kg
A Question of Scale
Now let's talk about an entire regiment. (Remember, we're only discussing basic infantry weapons, not special and heavy weapons).
The size of guard regiments varies enormously, as in real life. However, we have to pick a number, so let's just say an example guard infantry regiment (not even an average regiment, just an example) is 5,000 men and women. This is roughly in line with the Tanith First and Only (which changes sizes occasionally, tragically) and Ciaphas Cain's Valhallans. Assuming squads of ten with eight lasguns each, approximately 80% of the regiment's fighting strength carries lasguns. Therefore, a regiment of 5,000 has some 4,000 lasguns. For "Shipping Containers," below, which are included for a sense of scale, I'll use modern 20ft. shipping containers, which have a maximum safe load of around 20,000kg. This unit is called a TEU, or Twenty-foot Equivalent Unit, and used by international shipping companies as a hybrid of weight and volume.
WEIGHT OF AMMO NEEDED PER YEAR OF CAMPAIGNING
Regiment w/Lasguns 5,760 kg 1/4 of a shipping container
Regiment w/Autoguns 224,560 kg 11 shipping containers
Regiment w/Boltguns 1,872,000 kg 94 shipping containers
This means that the entire small arms ammunition requirements of a guard regiment can fit into about a quarter of a single shipping container, while such a regiment wielding autoguns (common among PDF and traitors--both of whom tend to campaign on the same planet they're raised, and presumably, supplied, on) would require just over 11 shipping containers packed to the brim with bullets (not including space for packaging, which I'm sure would be substantial). A hypothetical "Why doesn't everybody just get boltguns?" Imperial Guard regiment would need to be delivered to their destination with 94 shipping containers jam-packed with boltgun ammo. Note that I'm discounting space and weight needed to safely package ammunition, which I'm sure would be considerable.
No, Really. A Question of Scale
(all info about shipping containers and global shipping comes from this site) The Imperial Guard is bigger than a single regiment. It's bigger than millions of regiments. The size of the Guard is measured in trillions of men and women under arms, not including the PDF (which is, by many accounts, the larger group by far). We could fight all day about how many trillions of Guardsmen there might be, so I'll give you the numbers per trillion, and for 5 trillion (which is a number I think I saw in a codex at some point, idk I've already cited enough sources for tonight.)
Shipping Containers (TEUs) Evergivens 21st century Earth's Entire Shipping Capacity
1Tr w/Lasguns 50M 2,500 ~2x
1Tr w/Autoguns 2,200M 110,280 ~102x
1Tr w/Boltguns 18,800M 940,000 ~874x
5Tr w/Lasguns 250M 12,500 ~10x
5Tr w/Autoguns 11,000M 550,280 ~510x
5Tr w/Boltguns 94,000M 4,700,000 ~4,370x
(Note that, with an estimated 1 million marines, total Astartes ammunition consumption is virtually negligible in the scale of the Imperium. Their ammunition simply isn't the limiting factor--it's training, power armour, geneseed, etc. This is also how Space Marines can seem to have an unlimied number of sacred gold bolt rounds blessed by the bones of a saint or whatever.)
For the Guard, you can also see why even autoguns quickly become unwieldy at this scale. Supplying five trillion guardsmen with enough autogun rounds for one year of campaigning alone would require over five hundred times the Earth's entire global shipping capacity combined. This is just for rifle ammo, not taking into account grenades, promethium, autocannon rounds, heavy bolter rounds, mortar rounds, whatever it is that melta guns shoot, etc.
Equipping the Guard with "Why not just give everybody a boltgun?!?!?!" would multiply that entire operation by nine.
All of this stuff has to be loaded, by shuttle, onto intersteller voidships. These then have to transport through the warp, which is notoriously unpredictable. These ships require escorts, massive crews, and huge supply chains themselves. They might be delayed in the warp by days, weeks, or years. Such long delays are presumably uncommon, but on the scale of the Imperium, with its millions of worlds, they must still happen hundreds of times per day. At any time, a whole planetary campaign may be stripped of resupply for days or weeks. In this time, heavy support weapons might fall silent to conserve ammo, but the millions of grunts on the frontline would be able to continue fighting unabated.
This is a singular advantage held by the Imperial Guard, and surely makes up for having to roll one better on every die than any other faction (grumblegrumblegrumble). No other galactic armed force in the 41st millenium operates on a scale this vast (except perhaps for the Tyranids, who obviously have a completely different set of considerations)., and so no other faction must make the same concessions to logistics over oomph.
Comments