Historical, Alternate History, Modern Era or Future Tech, Weapons, Vehicles, Equipment and Tactics

If the goal is long range point shooting in a package that can still provide automatic fire I'd look more towards marksman rifles like the SCAR Mk 20 or the G28 (M110 in US service). These rifles are converted from more conventional assault rifles for the marksman role, both are theoretically capable of automatic fire and are accurate when point shooting out to around 1000m. There's also the M27 IAR, which is actually recently was developed into a marksman variant.

If you're interested in long range automatic fire, such as for fire support or area fire on longer ranged targets, something like the M240 with a heavier barrel and a scope might work. There's also the LWMMG protptype that's been floating around for a while, it's a belt fed machine gun designed to have a much longer range than the M240. It fires a .338 round and was supposedly able to hit targets accurately at over 1500m.

It all depends on what the purpose of the weapon is. Is it a general issue infantry rifle, squad support weapon, marksman rifle, or what have you. If it's a general issue rifle you'd probably want to avoid both of those extremes and go with something a little more basic, or maybe something modular that comes in a basic configuration but can be converted into a support weapon or marksman rifle.

Tuefel Hunden IV right, so use a combination of different arms. interesting video by the way.

Modular rifle sounds like an effective idea. Got a machine gun, marksman rifle and main infantry rifle in one.

On another note, what proportion of a rifle’s mass lies in its barrel? Is 5/6 a bit much? I was thinking of a scenario where the bullets are stretched out to create "needle rounds". They are made with the same volume but longer with a smaller diameter. The barrels are thus made smaller in diameter and weigh less.

A flechette projectile is what you are looking for. The US has toyed with that idea in the recent past.

See here for a general package of info from an imagur gallery.

Youtube vid on AAI's flechette rifle.

edited 4th Jan '18 10:34:30 PM by TuefelHundenIV

The barrel isn't usually that heavy, most modern barrels don't weigh more than 30-40oz. Most times the best way to reduce weight is lightweight furniture.

Flechettes are pretty questionable, I don't think there's ever been a successful flechette gun.

Flechettes can work but the US was looking for greater performance out of the weapons. The projectiles worked pretty well but there are some downsides to the projectiles. The first and most obvious is the shape. Unless they hit fairly close to nose on flechettes tend to have pretty lousy penetration and tumble very easily. Things like vegetation and brush would deflect them fairly well. More traditional bullets however are not as reliant and even if they go tumbling they tend to stay pretty nasty.

Flechettes seem to have a long metal dart within the bullet. What I was thinking of was keeping everything in the same shape and relative proportions but just thinner.

Archonspeaks, so the barrel doesn't account for much of the gun at all. How light could we get the unloaded M14 sharpshooter variant that fires the 3500 J rounds? The materials available would be from today and would be fed from a box magazine (sharpshooters wouldn't need to high a magazine capacity). It could have a recoil management system from an AA-12 to assist the sharpshooter.

On another note cartridge seem to have their gunpowder in the form of a powder. Powder takes up more space than a solid block of the same material due to spaces between granules. Is it feasible to use a solid block of gunpowder for a cartridge and how much space would that save?

edited 5th Jan '18 5:59:19 PM by zepv

The flechettes are not a bullet with a dart in it. What you are seeing is the sabot wrapped around it. That bit comes off in flight. The point of the sabot is to allow a smaller projectile to fit into a larger diameter barrel. The reason this is done is to take advantage of greater acceleration offered for a lighter round that would be used to propel a heavier and larger projectile. It imparts a good bit of speed to the projectile compared to just using smaller diameter barrel fit snugly around the dart.

If you want to see a unique take on flechette rifles check out the Russian made APS or "Avtomat Podvodny Spetsialnyy " or loosely translated Special Underwater Assault Rifle. It uses larger darts and a lower velocity cartridge but still more or less fits a elongated needle like projectile profile.

Another item you could consider is the design of the .408 Cheytac bullet which uses an elongated and very pointed bullet. The projectile is reportedly highly accurate at long range. There was some actual evidence to back this up but not quite what I would consider anything definitive. So if you google .408 Cheytac bullet you will get a idea of what they look like. There is also a .50 BMG projectile floating around somewhere with similar design elements.

edited 5th Jan '18 5:34:49 PM by TuefelHundenIV

Aright then. Probably not a good option for a main infantry rifle then.

Got another question (sorry if it's a bit much). What is the highest practical proportion of soldiers to have an under barrel grenade launcher attachment standard on the main infantry rifle?

The difficulty with reducing weight on an M14 is that receiver weighs almost a pound, it's by far the heaviest part of the rifle individually unless you have some particularly heavy wood furniture or something. The way the M14 works puts a lot of strain on the receiver (the bolt locks directly into it) which means it's difficult to make lightweight receivers for it. I think the lowest you could get it overall would be in the 7-8lb range, there are some lightweight models available now in the 8lb range and I'm sure with further tinkering it could get down to 7lb. Rather than some sort of complex internal system, a recoil reducing muzzle break could do the job. They're often used on M14s.

As for solid propellant, I don't know enough about gunpowder to say for sure if that would be possible but I know they've made caseless rounds which use a solid propellant block. They're not that much smaller than a regular bullet though, the gunpowder doesn't really take up that much space.

Caseless rounds have been...finicky.

Besides issues with the propellant block breaking inside the gun there's a heat management issue.

Normally, the casing acts as a heat sink, taking the lions share of the heat with it when ejected from the gun.

I updated my previous post.

zep:

I am guessing you mean solid inside the casing.

Cartridges are composed of a few general parts. The primer whether a center fire or a rime fire, the casing which is the brass bit, the bullet, and the propellant. Most propellant leaves a surprising amount of room in the casing. Part of that is a need for space for gas and combustion byproduct to expand into to build up the pressure to help push the bullet clear of the casing but also expand the casing neck. Loose powder granules have a well understood and comparatively easy to control combustion and expansion profile. The loose powder is also easier to ignite.

That isn't to say there are no solid propellants just the loose is preferred because it is not only well understood but it is far easier to work with.

Solid propellants have some pros and cons. The pros are you can easily shape or form your propellant giving you a fairly high degree of control of combustion patterns in a given propellant block. Technically speaking explosives are also a propellant and used in such a manner in various applications and shaping of solid explosives has yielded a lot of control of forces generated by the process.

Solid propellants can be used to more easily incorporate non-standard propellant components such as boosters, oxidizers, and other substances. The US military has experimented with this stuff before. It allows a broader range of compounds and even more sophisticated propellant parts to be created such as seen in rockets with solid fuel motors.

The solid propellants can be made to burn both hotter and cleaner as well as give greater control over the gas expansion profiles generated by the ignition and combustion process. They also tend to be fairly stable.

You can create molds or use a milling process to shape and form solid propellants.

The downsides are worth looking at as well.

The solid propellants require a higher degree of technical capability and more machinery to bulk manufacture the propellant.

The propellants are harder to ignite either requiring a multi-stage projectile such as was developed for caseless ammo, electronic ignition, or other more complex ignition system such as Electro Thermal Ignition which technically isn't standard electrical ignition, or even other exotic ignition systems such as a heated compressed air ignition.

The propellant does not handle shock an rough handling well. Without some sort of protective layer around it damage to the propellant can cause uneven propellant burn and lead to damage or destruction of items involved in the process or outright throw off the entire combustion profile.

The solid propellants tend to be a bit more expensive because of greater manufacturing concerns.

Solid propellants have lesser degrees of tolerance for being out of spec than loose powder loads which can lead to similar issues as if the propellant was damaged.

These are still fairly fast and loose details.

As for grenade launcher ratio that is something always up for debate and depends both on doctrine and practicality of the load outs. I can speak for the USMC squad layouts specifically. The USMC squad is composed of 3 four man fire teams and lead by a squad leader. The fire teams are typically composed of a Fire Team leader who carries the UGBL and most of the grenades, a regular rifleman, a light machine gun, and an assistant gunner. There has been some interest in possibly giving a second man a UBGL in the fire team but no one has actually acted on it. It likely would be handy to have a second UBGL gunner whose sole purpose is to carry the lethal ammo loads while the fire team lead carries smoke, flares, and lethal loads in a mix as needed.

There has been some substitution of UBGL's with standalone launchers such as the Milkor MGL or launchers that can be mounted under a barrel on a rail or quickly attached stock such as with the M-320. Which gained some popularity with some troops with the introduction of a holster for the launcher meaning they could pull it out and use it as needed and then return it to the holster rather than having it hang off of their rifle.

There really isn't a complete set of ideas or bits of doctrine on the matter but there are variations on it.

edited 5th Jan '18 6:24:08 PM by TuefelHundenIV

Archonspeaks, that sounds like a pretty good weight, especially with the huge rounds it fires

Belisaurius, looks like caseless rounds aren't that practical then

Tuefel Hunden IV, thanks for the info. Looks like powder propellant is the way to go.

Is there any way to overcome the overheating issues for the M14 so that it does not significantly affect it's performance as a main infantry rifle? In-setting it's a temporary step to another rifle. Perhaps some kind of cooling fin arrangement? Is that a practical possibility?

edited 5th Jan '18 7:19:32 PM by zepv

A heavier barrel with fluting could help with cooling and stiffen the barrel which could help with accuracy issues. The heavier barrel with fluting cuts would absorb more heat than the original barrel and have some low end improvement in how quickly it can cool due to increased surface area from the cuts.

Overheating wouldn't really be an issue unless you were firing on automatic for an extended period of time. If the rifle is fed from box magazines unless you're shooting off each magazine all at once and then replacing it immediately for like 20 minutes minutes straight it wouldn't be an issue. Note that the gun will definitely get hot, but when I say overheating I mean like to the point where the barrel is damaged. The way heat is handled most of the time for machine guns is interchangeable barrels, carried either by the machine gunner or assistant machine gunner if that's applicable. A heavier barrel would absorb more heat, but that becomes another weight tradeoff.

Additionally, if this is meant to be a general issue rifle you might consider a smaller round. The M14 was replaced because it was difficult to control while firing and not enough rounds could be carried compared to rifles with smaller cartridges. Something like the 6.5 Grendel could be cool, it's a middle ground between 5.56 NATO and 7.62 NATO and is supposedly quite effective at long range. I've heard of it being able to hit accurately at 1000m. There's also the 6.5 Creedmoor which is the hot new round on the block right now and also offers better performance than the 5.56 NATO, it's also accurate out to 1000m These two rounds are interesting because they have good performance at long range but are small enough to be used in AR-style rifles. I don't think either of them have ever been adopted by a major military force before though.

The barrel getting hot has other knock on effects before its hot enough to damage the barrel though. Heat shimmer distorts the visual picture of the barrel, heat bleeds back into the action via the breech and into the mechanisms even from a short period of non-automatic semi-auto fire of roughly 5 minutes which increases malfunction risk, there is the ever present unintentional fire hazard via a hot barrel brushing something flammable such as dry grass, cloth or something similar. Also barrels get hot enough they start to lose accuracy. There is rough semi-ideal middle ground that is really easy to go over or go below in terms of barrel temp. Plastic hand guards catch fire a surprising amount when you start running the guns hot even if wiped down of any possible lubricant or cleaning agent. The lighter barrels get hotter a lot more quickly and transmit that heat back into the weapon. 7.62mm weapon operating at similar tempos will definitely get similar heat effects. Another thing to remember is the more powerful the charge the more heat is going to be generated per shot.

The 6.5mm while interesting has had several articles written on how the 6.5mm Grendel has been overhyped. It has a reputation largely driven by the shooter market which is as much rumor as it is facts. I have some doubts about 6.5mm Grendel being reasonably accurate out to a full km. I might believe heavier round with more velocity but I have doubts about the 6.5 Grendel. The Creedmore might do it with both 120 Grain round but also a 3,000 fps muzzle velocity for one offering. The downside is the round is notably larger and more powerful than 5.56mm or the 6.5mm Grendel.

The standard 5.56, 7.62 NATO and .50 BMG bullets all have a similar ratio of caliber to length from what I've seen, roughly 4.5, while spin-stabilized bullets in general are said to be able to reach as high as 7 before they become too difficult to stabilize with rifling; Fin-stabilized flechettes can go much higher, but the point is, there is room for significant difference with regular bullets too(or saboted subcaliber bullets for that matter).

Problem is, reaching the desired muzzle velocity may require a more elongated barrel; You have less volume behind the equally-heavy bullet to fill with expanding gases of probably-similar peak pressure. How much more elongated, and how thick it would then need to be in order to be stiff enough, seem to be the questions.

When I say gets hot I just mean like hot to the touch. That happens quicker than people think.

I agree that the 6.5 was definitely overhyped, most articles about it when it first came onto the scene were pretty breathless and made it out to be some sort of miracle round. That said, I've been able to hit targets at 900m with a 6.5 Grendel Howa and I'm sure with some practice (and skill, I'm not the best shooter around) you could get it out to 1000. Don't forget it also has something like double the energy of the 5.56 NATO at similar ranges.

Tuefel Hunden IV, how much extra weight would the fluting give the barrel in the case of the M14?

Tuefel Hunden IV and Archonspeaks, so if we use an M14 round for a general issue rifle would that be enough to get the knock on effects Tuefel Hunden IV mentioned? Might go with a smaller round at first until sometime in the future of the timeline when something is invented that reduces that amount of recoil to something roughly manageable. If the Creedmore is used for the general issue rifle then the rifle would that be enough to prevent the knock on effects?

Man In Grey, thanks for the info.

If a rifle bullet has roughly the same energy as a shotgun round can it be used as an entry shotgun? What if it only has 3000 J instead of the 4000 J you usually have in a shotgun shell? Would the rifle would need a triple round burst or a special entry round that fitted in the rifle?

edited 5th Jan '18 10:28:01 PM by zepv

Any round can heat up a barrel like that. As he mentioned there's a middle ground, but that comes to the operator and not the rifle typically. As long as you fire carefully and give the gun time to cool off after extended periods of firing you can avoid the worst of it.

Fluting removes weight rather than ads it. A fluted barrel has grooves or indentations cut into the outside. [1]◊

Zep: As long as the shooter isn't blazing out round after round in high intensity combat. Using something akin to the M-14, maybe give it a fluted barrel and go for the 7.62mm EPR round as your place holder until someone develops an alternative that works better. The typical 7.62mm Fire arm should have enough room to chamber the longer 6.5mm cartridges but I can't remember exactly how long the Creedmore is. The Creedmore is notably bigger than the Grendel.

Unless you chose to use a shorter barrel the Howa bolt action not only has longer barrels than the average AR, given most hang around 16" to 18", but being a bolt action also has benefits in terms of long range accuracy over most semi-automatic fire arms. The 6.5mm Round that most resembles a 5.56mm tops out around 90 grains but has some good velocity behind it. If you are firing the heavier 100+ grain rounds out of a 22"-24" barrel your going to get better down range performance.

As for lb for lb energy at 1km the 855A1 EPR for 5.56mm compares favorably to the 90 grain 6.5mm Grendel in terms of energy they are actually rather close. The 6.5mm is still higher but the gap isn't large. That is for the 90 grain round. The heavier one like 120 grain offered by Norma out of a 16" barrel does have higher energy at 1km but nowhere as drastic as double the energy because of reduced muzzle velocity out of the shorter barrel. Something closer to 150-175 more foot lbs.

The 6.5mm Grendel also can't fire the longer heavier bullets through an AR as the cartridge length is too long forcing them to use lighter and shorter projectiles. They have ones built for AR that are shorter but the ones you can load through the bolt actions like the Howa are going to be a better offering. Bolt actions can also use comparably more powerful loading in most cases.

There is also increased overall recoil from heavier rounds. Nothing horrible but enough to take note of at longer ranges for semi-auto fire arms.

If we are looking at 7.62mm NATO caliber the M80A1 EPR gives a notable boost to 7.62mm rifles. The thing starts being almost scary. I would bet this is the round that keeps the 7.62mm NATO in USMC sniper rifles longer unless they find something different.

The EPR have a somewhat unique advantage in that they were built to do several things from the outset as a sort of general purpose round. Defeat heavier cover at longer range, have better soft tissue damage at longer ranges, and penetrate body armors that would normally stop their older counter parts. The 5.56mm EPR was blowing through Kevlar at 1km and was able to defeat some body armors that were rated to stop 7.62mm ball. That is a notable improvement over the old green tip. That arrowhead penetrator helps quite a bit.

edited 5th Jan '18 11:16:53 PM by TuefelHundenIV

I believe the one I used had a 16" barrel. That's a bit on the long side for an AR but nothing crazy. Obviously comparing a bolt action to a semi auto is a big difference but I was only using that comparison to illustrate the long range capability of the round.

As for the double the energy part, it's more pronounced in the 600-800m range. I should have clarified that in the original post, it definitely doesn't hold as strong an advantage at 1k. I've never seen a ballistics chart for the 5.56 EPR so I'm not exactly sure on this, and I know the EPR has some different terminal ballistics thanks to the penetrator, but comparing 6.5 Grendel to high quality .223 the 6.5 has double the energy on target at 600m, and the gap only closes at around 900m. As you pointed out as well it's also possible to get a much larger bullet, since the 6.5 Grendel uses the shorter casing the 120 and 140g rounds can both still load easily in an AR.

The Creedmore is a just a little longer than the 7.62 NATO (71mm to 69mm respectively), I believe 7.62 firearms can chamber it though I wouldn't suggest trying that at home.

So it might be worth using the Creedmore provided your sure it will fit the weapon and it can handle the pressures. I don't think I would risk it in the stock barrel of an M-14 but maybe something with a heavier barrel and thicker chamber wall. I would also want to change out the bolt for something more robust if possible.

Mid range around 500m-600m I could easily see being the case. For whatever reason the mid ranges always seem to get weird in terms of ballistics even among cartridges that have similar weights and muzzle velocities. I would argue round weight and shape tends to do the most interesting thing around these ranges.

Though given what I saw for estimates for 6.5mm Grendel at 1k it still has few hundred foot lbs of energy to its name. So does the EPR but that one has a downside for AR platforms in that the round is a bit hotter than what is normally used. A ground up piston upper in 6.5mm would likely fare better.

I would be surprised if we keep the current configuration of M-16 without changes to the barrel at least. I would find a different bolt to use as well. Not sure how a piston rifle would handle it but from what I remember of AP Black Tip rounds those were also a bit hotter than the normal round and they wanted number fired estimates tracked as close to the round count as possible because they were hard on the barrels.

They actually do sell M14s chambered in 6.5 Creedmore. From what I've heard it's got some good range on it, potentially 1000m with the right setup. The M14 parts are pretty tough, I would be surprised if they needed all that much reinforcement.

From what I've read about the Grendel it was designed from the ground up for mid-range performance, with the idea being that most combat takes place in the 200-800m range. It definitely performs well there, I'm no expert on ballistics but I would assume due to the fact that the bullets are heavier while remaining streamlined as you said.

The performance of 6.5mm rounds in general is pretty interesting, and I wouldn't be surprised if it was something the military looked seriously at. Like you said I think we'll be seeing some serious changes to our basic rifle platforms in the near future, and based on the fact that SOCOM has been pretty pleased with the 6.5 Grendel and .300 Blackout firearms they've gotten I wouldn't be surprised if a lot of attention was directed towards a new midsize round. I definitely think you're on the mark with piston being favored over DI as well.

With the hotter rounds DI starts to become a bit of an issue. Don't get me wrong DI works but there is a lot going for the pistons.

Though I am starting to wonder what sort of 20 minutes into the future kind of rifle tech I would find interesting. I keep wanting to see something exotic or different. Maybe something like modern combustible casing.

You mentioned earlier the new EPR runs hot, I'm not surprised that causes issues. I've had a generally positive experience with DI rifles, though I have seen a few failures to extract and thing like that. That said, gas piston is definitely the way to go. The short-stroke piston system on newer HK rifles is near invincible, and their newest rifle (HK 433) looks phenomenal, if pricey. I also remember hearing about self-cleaning piston rifles that can go 50,000+ rounds without cleaning, though I'm not sure how accurate those claims are.

For 20 minutes in the future, I think we'll see some big changes to ammunition. The Army has made some really awesome progress with cased telescoped and lightweight polymer cased ammo, and I believe we'll see cased telescoped hit primetime in the next few years. There are a couple interesting interviews with the LSAT program officer floating around where they talk about the new ammunition, I'll see if I can find them. I think we're gonna also start seeing a lot more modularity on basic platforms and tool-free rifles as well, with how reliable the new piston systems are there's been a renewed focus on the "user experience" so to speak. Things like better ergonomics, easier controls, possibly even round counters and AR overlay optics.

Finally, I think we'll see a lot more suppressors. New designs are reliable enough for heavy use, and I know the Marines are trying out some cool stuff with them. Once they get a little cheaper I think they'll become a lot more common for infantry, and we might even start seeing integrally suppressed rifles issued.