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Semicooperative: Breaking Down the Bolter



Warhammer 40K's Bolter family of weapons are the iconic weapons of the Adepta Astarters or Space Marines. They're a classic grimdark weapon, but they also have some...interesting features. So, let's take a minute (checks read time), okay, more than a minute, to look at the design of the Bolter and how it compares to modern weapons.

Bolts

The Boltgun fires Bolts *looks at notes* yes. Which is a great term when talking about firearms because a prominent part of guns is the "bolt", but anyways. Bolts are, canonically, .75 caliber explosive reactive rounds with a solid rocket propellant and a shell casing. .75 caliber is 19.05 millimeter, so it's very high caliber for an infantry weapon, but very low caliber for a cannon (cannons are usually 20mm or greater, but that's more what you'd call a "guideline"). 20mm is rare, but not unheard of, for an infantry weapon and is usually a support weapon for a squad whereas every space marine has a Bolter.

The round is explosive reactive meaning it has an armor piercing tip and, once it enters a target, will detonate on a slight delayed fuze. We have these in the real world, they're called Armor Piercing High Explosive (APHE). More accurately, we "had" them. They're basically obsolete at this point. Most militaries stopped using APHE for tanks before the average person reading this was even born. They still see some very limited use in specific applications, but are a far cry from common. The reason APHE is not used, is also relevant to the bolt rounds.

Most people probably picture the explosion as spherical, but physics and real world trials show that a round of ammo moving at high speed and exploding produces a conical explosion in the direction of travel i.e. it will explode towards where it was moving. When the US Army compared the damage of APHE, solid AP and sub-caliber APCR (softer outside with a harder metal in the core), the conclusion was that difference in damage inside the target was marginal. Additionally, an APHE round had less structural integrity because of the interior section with the explosvies, so it couldn't penetrate as much armor.

Additionally, the US Army, with it's much later OICW project, discovered that 20mm (bigger than a Bolt, mind you) had a a really unimpressive amount of explosive mass especially with the amount of interior space they were devoting to electronics. Note, these were not armor piercing shells, so they had thinner walls than something like a Bolt would have to. The Army ended up having to go with 25mm for the XM25 to have enough explosive mass to do meaningful damage. To put it simply, not only is the bolter not a grenade launcher or even particularly close to one, but the explosive effect probably doesn't add much to the .75 caliber shell. If they really need to put explosives in the shell, a hollow charge would probably help more...or HESH because 40K is both weird and British...that was obscure even for me.

The round is both cased and frequently mentioned as having a rocket engine. This might seem counter intuitive, but actually does make more sense than most of the gun to be honest. A rocket motor would present the advantage of typically range and a fairly consistent velocity (which translates to more predictable energy and effect on target) compared to a more normal bullet. The problem with rockets is that they need time to accelerate. For example, if you look at the Gyrojet, a rocket pistol, it barely has any speed when it leaves the barrel. In fact, if you put on some heavy gloves to not get burned, you could easily hold the bullet in the barrel of a Gyrojet with your hand. It didn't hit maximum velocity until about 20ish feet away from the barrel which is obviously a huge issue if you have to use it at close range.

A way to solve this is to use a kicker charge to get the rocket out of a launcher at a useful speed before the rocket motor ignites. If you watch a video of a TOW or Javelin missile fire, you'll see what I mean. There's a small charge to give it a sudden burst of speed out of the launcher before the main motor kicks in. Rockets can also have stability issues, but as I have never seen that mentioned canonically, I'll just assume they have effective stabilization system (deployable fins, a machine spirit to make micro adjustments, etc). This would also help a lot with recoil. Since the charge moving the round out of the Bolter, doesn't have to get the Bolt to terminal velocity and carry it to the target by itself, it could be a lot more manageable than a charge that has to send a round flying 200-300meters on its own.

Magazine, Belts and Drums, oh my!

One thing that stands out when looking at a lot of Bolter magazines is that they have a lot of curavture. Usually, a magazine curves because the ammunition it's carrying has a taper i.e noticably wider at one end than the other. If you were to look at 8mm Labelle it has a huge base, so the magazine for the CSRG 1915 is so curved it's a half moon, but for something like .45 ACP in the Thompson the magazines are perfectly straight. Bolts have basically no taper, so I have no idea why so many Bolter magazines are sickle shaped instead of straight. Maybe a lot of Bolters use non-standard Bolts with a more aggressive taper that require this curvature? If so, they seem to be more common than standard Bolts.


Chaos (and some pre-heresy loyalists) also seem to be under the impression that you can just jam a belt of ammo into a magazine well and make it a belt-fed weapon? This is not how any of that works. The only weapon I've operated that can switch between feeds is the M249 and that uses two different feeds because, spoiler, you need different parts to retain and drag a belt through the weapon than you do to simply pull rounds out of a magazine. This may seem tedious, but I have no idea how you access the firing chamber either. My best guess is that Chaos Space Marines just turn the Bolter upside down, dangle the belt down until they think it's in the right position and just close the bolt (I'm using little case "b" for the part of the gun...Ill probably forget that soon) and hope the belt doesn't fall out when they turn it rightside up. Or they just throw it to a cultist to figure out and get a new gun, that would be a very "40k" solution.

Speaking of belts, where do the belt links go? I have never seen any artwork or heard any description of belt links being ejected. They kind of look like disintegrating metal belts i.e. they disconnect from each other as you fire. They could be continuous metal belts based on construction, but we never see a belt sticking out of a fired weapon. I guess we just assume they eject out of the same port as the casing? Maybe there's a mini warp gate in the Bolter that sends the belt links to a random planet in the Eye of Terror...still would not be the most insane thing in 40K.

The drum magazines throw me off a little as well because they don't seem to have any method to feed rounds into the weapon. Normally a drum needs some sort of winding mechanism to feed rounds into a weapon designed for box magazines, or exists to neatly hold a belt of ammo for weapons that have a belt feed. Bolter drum magazines lack either of these and just appear to be a box holding a collection of rounds near the magazine well which...obviously wouldn't do anything.

I Have No Idea What This Is?

I cannot find any information on a canonical operating system for a Bolter. It almost certainly isn't blowback because physics say "no" (the mass you would need for the bolt would be ridiculous). I have a lot of reservations about a gas operated system because Bolters don't have much (if any) barrel and gas operated weapons need a gas port at a specific location to get the right pressure curve and I'm just not convinced the barrel of a Bolter would allow that kind of placement but I can't definitely say no. That being said, maybe the machine spirit did it i.e. the operating system is pure electronic. That would give it high consistency and make it resistant to a variety of malfunctions even if it would be needlessly complex.

There is no discernible system to mitigate recoil, BUT Bolters do have a ton of internal space that isn't exactly accounted for. Even though the bolt wouldn't be able to travel very far, there could easily be room for a pneumatic system or something internally.

The ejection port and charging handle are technically above the barrel. Despite how odd it may look when you realize it, there's nothing mechanically "wrong" with this. It would make the chamber more difficult to access if you want to check to see if your your loaded or have a problem (although I imagine both of those things are what servitors are made for) and it would involve more engineering vs just having them all in a line together, but it is mechanically possible. It's just weird and doesn't seem to serve much purpose.

There's a tab on the upper front of the weapon that slightly resembles a front sight post, but definitely isn't. For one, there is no rear sight post. Even if there was a rear sight post, it's so thick that it would be useless as a sight even if your were in the same room as your target. It's also directly in front of the mounting rail that we normally see high-zoom optics fitted to which...why? Do you desperately need a lego brick blocking out part of your sight picture? It appears to do literally nothing.

Heavy Bolters are listed as having an electrical trigger. This is a feature you would ideally want on a precision weapon because it allows for really good consistency on the trigger pull and removes excess movement before the round fires..but why would you put it on a heavy machine gun? All I can think of is that Heavy Bolters are such a common vehicle-mounted weapon that allowing the trigger to directly interface with the vehicle could make mounting it or using it mounted easier. Normally, you need a solenoid to fire a typical trigger from inside of a vehicle, so I guess this would be better, but feels like a stretch to be honest.

Can You Fire It?

Would it break your arm to fire a Bolter? Of course not. Don't be stupid, it would break your wrist. This is less because of raw power or high recoil and more because of the dumpster fire of ergonomics. The pistol grip is the end of the weapon, so you have nothing to brace it on. All of the weight is forward and the center of gravity is well forward of your grip point. You're basically bracing all of the recoil of the weapon solely on your wrist.

If you could slap together a decent stock or some other way to manage the energy of the weapon and brace it against yourself, it would be heavy and awkward, but usable in semi-automatic. Four round bursts and fully automatic would be unusable by normal human firers without some kind of bipod.

The mass of the Bolter alone would eat a lot of recoil, it doesn't use a full 20mm propellant charge and most Bolters have a really considerable muzzle brake and all of that is before any potential internal dampening system. The recoil probably gets overstated somewhat as does the explosive effect, but the size and weight would certainly be ridiculous unless it's literally hollow.

Naturally, if you're just cheating and being a super human with armor that balances the weapon and manages the recoil for you, you can just use the stupid thing one handed...and considering space marines are the primary user of Bolters, I doubt they would request changes to make it easier for us plebs to use it.

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