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Let us sit, and talk about the size of solid munitions

Firebrand

Firebrand

Inactive Member
As many of you know, there were... issues when I began preliminary work on designing 20mm ammunition for a possible LASR replacement rifle. People felt that such a thing was "too big", "Too impossibly heavy" and "No-one would ever use a 20mm or larger round as a primary weapon in the setting".

So I started looking around for examples of a reasonable bullet size, and I realized something important: Round Calibers are absolutely messed up.

This all started when I wanted to replace the primary service rifle for troops in PA, the LASR.Which, as we all know, fires 7mm rounds. The rounds I were making were 20mm rounds, Which everyone said was completely out of line and something that no PA rifle should ever carry. So I went and looked that the caliber for the current Yamatain non-armored service rifle, the Type 33, and saw that it fires 12.7mm rounds faster than the LASR.

Okay. Okay. So I looked around at the kinds of grenade launchers to see if 20mm was too huge and look what I found, 50mm grenades. At this point I just went "What." and went to look at the Nepleslian Powered Armors.

I did not find a soothing balm for my confusion, instead I found even more confusion. Take, for instance, the NAM 'Light' Coilgun. Which fires 30mm rounds. Or take a look at this "average" 30mm Triple barreled machinegun. Or the UMD, which uses rounds which are the diameter of a soda can. So about 52mm.


C-Can we talk about this? I feel like I'm being unfairly singled out, and Wes is being called crazy unfairly on his insistence on a 30mm caliber round, when kinetic weapons of these calibers are common among other powered armor.
 
The trope "Sci-Fi Writers Have No Sense of Scale" is a really old one, and one that is often true, but we're trying to fix it. Really! There are things that are out of proportion like the Mindy's 50mm shoulder mounted cannons for an example; 50mm is realistically as thick as her wrist. A standard 18 round ammo drum would realistically be the size of a one or two gallon container even.

Size being too much or too little however, is all about context. In real life for an example, we got 40mm grenade launchers. Not rifles, but actual grenades. In that context, it's ok. With the NAM coilgun though, it's not a popular piece of tech for several reasons, as I pointed out in the shoutbox. I suspect it's the same for the 30mm chaingun too - the creator didn't get along with many people, and simply did things his way. As a result, GMs tend to simply ignore gear that they feel don't fit the setting, and those are some examples of such kit. Meanwhile, with the Type 33 rifle, the context for this matters too. It's meant for unarmored troops in ships or supply line workers who find themselves attacked. It's actually completely anemic in comparison to the LASR, but tries to make up for that with a big round and sacrifices capacity in return. However, because they're second or third line troops, reloads are always handy. Not so much for a soldier out in the field. They need small and plentiful ammo.

Again, I said, getting scale right and keeping in mind its practicality is a problem, and it's best we don't keep making this mistake as we go along. I'm sorry if it's given you any grief.
 
I have a brass casing of a 20mm round that I acquired during a CIWS demonstration on a U.S. Navy ship, which helps me visualize how they'd work in a power armor weapon. I think it would make sense for a Daisy to have a 20mm (conventional) rifle since they're somewhere between infantry and tanks.
Yeah, the original 30mm was more for some sort of half-cannon half-grenade thing like the XM25 uses, but it was probably a bit much.
 
The reason 20 mm doesn't work well for the Daisy is that it's human-sized. 20 mm is big. It's what fighter jets shoot out of their automatic cannons.

I went with 7 mm because I could pack a lot of rounds in the weapon, fire them really fast and not have a lot of recoil. It meant very accurate fire. If I wanted to take out a tank, I wouldn't use the LASR, except maybe the SLAG. That's not what the weapon was for.

Switching to 20 mm means far fewer rounds or a more bulky magazine, a lot more recoil and possibly less range. It also means repurposing the rifle.

It makes more sense to create a new rifle, if you want something that will have a larger "wrecking" range.

That said -- you've got the Plasma Rifle if you want to do that.
 
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It also needs to be pointed out that all of the examples of large caliber weapons you just listed are Nepleslian, not Yamataian. Nep PAs have always been bigger, bulkier, and built more like tanks to start with, with proportionally bigger guns to go with them. Yamatai relies on technical superiority and sheer quality over the bulk and brute force the Nep forces favor. Yam armors are usually only slightly larger than the people wearing them, and while they enhance strength and durability, they still rely much more on traditional infantry style equipment, just because of that size. Nep armors, on the other hand, start out with the Hostile, which, despite only being about 7ft tall, weighs in at 2 tons. It's built like a tank, and can handle proportionally larger weapons to go alongside that. Compare this to the Mindy 3A, just as an example, which is only slightly larger than it's user, and weighs, on average, about 100kg. Literally 10% of the Hostile. Trying to arm it similarly is just ridiculous.

I'm not saying that all of the weapons are perfect, but you have to keep in mind a)that velocity plays a much bigger role in the impact of a round than mass ever can, proportionally speaking, and b)that Yamataian armors are nothing like traditional "mecha". They're exactly what the name says, powered body armor. Trying to arm them with superhuman sized weapons is an exercise in futility, because they're not superhumanly sized themselves.
 
If the comparison to Warhammer 40k helps, Yamatai is most similar to the Eldar, while Nepleslia is more or less the Imperium's Space Marines. The weapons that suit Yamatai best should be more graceful, not brute force.
 
Ergo, I think I've come to a compromise solution to fit everyone, with the help of Doshii Jun

The new main kinetic round ill propose will be a 10mm boattail round, an enlarged version of the 7mm round used by the LASR with a few added tricks. This 10mm round will be used for a service rifle, and for a Squad Automatic Weapon analogue (Similar to how he M4 and SAW both use the same round).

The 20mm round will stay, but for a completely different purpose. It will, hopefully, be used for a sniper rifle, based on existing 20mm Anti-Materiel rifles.

If people agree with me that 50mm is far too large for a Yamataian PA shoulder mounted gauss gun, I believe we could develop a 20mm or 30mm one as well. Also floating around in my head is an idea for some form of mortar- 50mm, that can be attached to an armor's shoulder hardpoint to provide indirect fire capability. Another loony idea I had would be to take the SLAM and modify it to mount to an Armor's shoulder hardpoint
 
That honestly doesn't sound too bad, and replacing the 50mm with a 20mm version that just uses a higher velocity projectile would be a lot better I think.
 
I'm okay with that, but I would like to keep the classic 50mm ones around too, and phase them out slowly.
 
Honestly, I think it makes sense to downsize the Gauss like that. It's role of being the big boom weapon that anyone can mount is just as fulfilled by a hypervelocity round, and it would honestly be more effective against heavier units like Reapers as a result. Smaller round, higher speed, better penetration.
 
Honestly it doesn't really need to be smaller per say, go with a twenty mike mike diameter but you can either lengthen the projectile or increase its density to keep the joules in the same neighborhood. You can also include secondary effect munitions (akin to the 12.7mm RAUFOSS).
 
I mean the mass/density of the round can stay the same to keep performance the same but tweaking the dimensions to make it more logistically friendly.
 
Except that doesn't work. If you make your 20mm rounds as massive as a 50mm round, all of a sudden, you've just multiplied the weight of a SECONDARY weapon's ammo by 2.5. That's a lot of weight for a weapon that is going to rely on speed to make up on the mass difference already. Mass times Velocity Squared, we can make up for the mass much more easily with velocity, so there's no point in making superdense rounds. MAYBE a penetrator core, but a superdense round on the whole is just silly. Again, this is Yamatai. They don't go heavy and bulky, they go lightweight and graceful.
 
I just want to point out there isn't much need to make a PA SLAM, since the PAs already have missile systems they can equip. Just make new missiles for them. Also think agree with making the rounds smaller and faster. Because while honestly I think it's a little ridiculous that every energy weapon seems to go at a speed of c, that seems to be someone most settings do(even DBZ) but because of that speed, slow heavy rounds are rather impractical. If you can dodge a shot moving at c in a PA, you want to get the kinetic rounds going as fast as you can to try to compare, not slower, otherwise they just wont hit.
 
The other part is that it's just so much less energy intensive to accelerate a round to higher speeds at a low mass than a high mass. It's why almost every good sci-fi writer uses the hypervelocity rounds. Honor Harrington is one of the bigger examples, but there are plenty of others out there. A 3mm round moving at 3000m/s has WAY more kinetic force than a 7mm round moving 1000m/s, but is much, much easier to get up to those speeds. Once you get rounds moving fast enough, the shock is enough to cause catastrophic damage to the body, even if the penetrator itself wouldn't, but they're also far more capable of penetrating armor and other materials as a result.
 
Yeah missiles are pretty much the best indirect fire you're ever going to find, if it was more cost effective than it is in today's battlefield it might be fielded more often; but as of now a field of expeditionary marines with modern artillery can have a good effect and for much less cash than a truck sporting missiles.

Although in a future where you tack tiny missiles onto PA, why sacrifice the guidance capability for relatively antique barrages.

At the same time I do kind of like the idea of some burst grenade explosives for a nep power armor, basically I mean MK 19 automatic coupled with a XM25

You know to like bypass defilade cover too just like missiles could. It's still pretty advanced and cool
 
Why go for slow, guided projectiles when we can have cannons shouldermounted that will penetrate several feet of metal? Get rounds moving fast enough, and they'll penetrate any cover that you could effectively fire around with missiles/airburst.
 
My understanding is that nep lacked symmetrical technology development regardless and used slightly more primitive tech in general when compared to the apex of the setting. I suppose in my own perspective missiles and grenade still retained a purpose despite your super cannons that shoot faster, farther, and more accurately than anything else out there. I presume you would still need to know exactly where you're shooting to kill the enemy beyond cover, could the missile not garner some height and then effectively arc their way back down and track their own targets independently? Probably the best thing about a missile is despite the slow speed, It's a fire and forget weapon and might still have some viable tactic when coupled with cover use. Despite cover not being ridiculously useful either apparently.

Lol
 
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