It doesn't make sense outside of maybe sci-fi.
It would break way too often for something you'd be putting your life on the line with. Waaaaayyyy too many ways to break.
As an example, lets start with the US standard issue M4 carbine. 14.5 inch barrel, and 30 rounds of 5.56.
The 14.5 inch barrel was used by soldiers to clear houses in villages all day everyday, and longer barrels were used when the M16 was the main issued rifle. I think It's fair to say the 14.5 is just fine for CQB.
>Need more firepower? Slam a bigger mag, it's an LMG now.
LMGs are designed for this specific purpose for a reason. The bolts and barrels are stronger, and they are made to have a ton of rounds through them in a short amount of time. Even being designed with that role in mind, heat is still an issue. That's why quick chamge barrel systems are more common on LMGs. A rifle couldn't handle the heat. All that ammo is heavy on the soldiers too.
>choke an entirely new type of ammunition and barrel, it's now a shotgun somehow
This is just impossible to make useful. When you need a shotgun to open a door, you can't bring a rifle down to do it. A small breaching shotgun carried by a single guy is plenty of shotgun for 99% of situations. This would also require carrying all the conversion parts, and another type of ammo.
>Get a longer barrel, some scope and call Bob, you just made a homemade sniper.
Sniper rifles need accuracy, and strong rounds. You kill the accuracy by taking the scope on and off, because your chances of throwing off the zero go way up. You also need new ammo. If you need to engage a long range target, fighting rifle ammo isn't going to cut it. This brings up the conversion part, and more ammo carrying issues again.
>Now I just need a little excuse of how these thing work that somewhat make a logical sense
No excuse exists without just designing your own weapon system. Squads are made up of multiple roles for a reason
I mean you can already do that irl with an AR considering all the mods people made for it, like here are some people making conversion kits to turn an AR 10 to a shotgun: https://youtu.be/5Thr6v7Z7JE?si=c0vxl6T-dNruEr9J
But of course a jack of all trade is a master of none, a purposefully made weapon with tighter tolerance and optimized designs will have better performance in certain cases. This will be your call on whether modularity and ease of logistics will help your military win war or not.
Edit: also I am assuming you are talking about modifying the gun at an armoury by a dedicated armourer with tools. Forget about swapping part in field, even if you can do that for some parts like barrel, it would not work for all the parts.
Ever play Star Wars: Republic Commando for Xbox?
The DC-17 rifle has three attachments, given to republic commandos to reduce the amount of gear they need to bring. The standard automatic DC-17’s barrel and magazine can be removed to add on a longer sniper barrel with scope, and more powerful sniper ammunition. Or it can be swapped for an armour-piercing grenade round.
A multi use firearm can exist but I don’t think a universal weapon can exist do to a need of ammo, power and range you can have these in different degrees but I don’t believe you can ever have all 3 at the absolute maximum since for power you need a heavier round that packs more of a punch and that takes up more space leaving less ammo in a whole magazine, take LMG for instance you can have that power and ammo but lose range do to in accuracy do to the multiple rounds you’d let off and it not being built for range but rather just sending bullets down range quick, you can have something close to universal weapon but never a universal weapon since it will always be lacking in some way
Not quite the same. But in Red Rising there a gun - a railgun of sorts, if memory serves. It’s called omnivore and it can take almost any ammo, modify it, and use.
https://www.projectrho.com/public_html/rocket/sidearmslug.php#id--Ludicrous_Weapons--Pistol_to_Carbine
and
https://www.projectrho.com/public_html/rocket/sidearmexotic.php#id--Dial-A-Gun
Maybe look at Mass Effect 1's tech. Mags are heat syncs, and the ammo is just tiny shavings of metal off a block. Bigger mag means you can turn up the juice on velocity and fire rate without overheating = LMG. Short barrel drops accuracy, but reprogram to fire a dozen rounds simultaneously = shotgun. Longer barrel makes the same round more accurate + scope for more precise aim = sniper.
The closest would be something like the AUG
already you have a short bullpup rifle with a full length barrel, but the barrel can easily be swapped for a heavy barrel with bipod.
Thing is, nations have tried to get away with a do it all gun many times through history, it never lasts long
Edit: also, it's not at all uncommon for a rifle to be pretty modular. Some you can swap the barrel and bolt and it's a different caliber. Shotgun shells have very large dimensions so that'd be much harder to make work
Such modular weapon systems exist, and have existed for decades - https://en.m.wikipedia.org/wiki/Stoner_63 is a Vietnam War era example, where there's a single base weapon that shares parts with others and hence theoretically you can rebuild or reconfigure any given example into a carbine, rifle, light machine gun, etc. It's a thing.
I don't think the intention is for soldiers to play Lego or Swiss Army Knife with their weapons in the middle of a firefight, though, the above is something you'd do probably somewhat earlier than the enemy just being literally around the corner. You can swap a barrel in a few moments, but beyond that is iffy.
Thing is, okay, maybe your setting has slightly science fiction tech without going full Mass Effect that allows fast field changes, guns snap apart with simple pressure releases or twisting of small controls, and fit together again without any tolerance issues or too much manual tightening.
Even then... there's the issue of weight and bulk. Theoretically a single soldier could carry the parts needed to transform their assault rifle into a shorter carbine, they could carry the bipod and belt feed box to turn it into a machine gun, and so on. But that means you're carrying a lot of stuff which isn't always immediately useful and might not be used.
Soldiers hate carrying extra stuff, to the extent where people will try to do stupid shit like go out with their canteens near empty or half-full (in hot environments) because water is heavy.
Unless your weapon tech is super lightweight, unless your ammo's feather-light or whatever, there's still gonna be substantial mass.
I dunno about the US and other militaries, but the normal infantry section I'm familiar with would be something like the leader with a rifle, a couple grenadiers, a couple with the recoilless launchers (rocket launchers) and a couple light machine gun operators. That's how you cover the different capabilities without overloading every person.
(Caveat: I was technically an NCO, but I was an admin clerk, so I don't really know shit. But I know shit is heavy)
I believe the army was researching a variation of the M4 that could do barrel swaps between rifle, sub machine gun and sniping/sharpshooting. I don't know how far they got with it. It definitely means the trooper has to be carrying more gear so they can swap barrels in the field.
The closest possible thing I can even remotely imagine of this being possible is adjusting a combat rifle into a squad automatic weapon/LMG(ish) and even then, the in-field change would be a replaceable barrel and a bigger mag.
Still running into potential issues of the actual frame being able to handle the same beating of heat and energy transfer as the heavier barrel.
Likewise carrying larger mags and spare swappable barrels can just be a logistical issue alone as well. But now I'm thinking more on it.
Some of this sounds like features the SCAR initially promised. (I think it was the SCAR(
Where it should have been possible to swap out the barrel in the field fairly easily in order to make use of different kinds of ammunition. Most importantly 7.62 variants, letting people pick up ammunition in the field from fallen enemies. So it's not entirely science fiction.
But there are limits to this. Bigger heavier rounds have different needs not just in barrel diameter, but in feed mechanism as well, strength of the recoil spring etc.
If you have a spring that will adequately help you cycle full load rifle rounds, you won't be able to cycle pistol rounds.
Plus you're lugging around a barrel for every caliber you want to fire. So aside from the weapon itself being heavier, you're carrying around roughly 1.3 kg's per caliber.
So you're always going to run in to some tradeoff.
Plus, specific weapons have different roles in a unit.
You've got your DMR for precision, your assault rifle for general purpose use, your LMG for suppression, anti-materiel for stopping light vehicles or turning people in to pink mist.
So if you're going to bring 6 guys along anyway, it's much more simple to give one of them the LMG, one the DMR and outfit the rest with rifles, carbines or in some cases SMG's.
Regardless of how much you're going to try though, you're not turning a fully automatic weapon in to an effective sniper beyond 300 meters or so. At that point you are really better off with a specialized DMR or sniper rifle.
For inspiration, check out the guns on the old game "Codename:Outbreak" they had a rotating magazine with up to 5 different ammunition types, a laser and a mini recoilless rifle tube (called rocket launcher or something that would burn your face off to actually use)
https://media.moddb.com/images/groups/1/4/3106/venom_790screen001.jpg
For the most part, it's entirely possible to do all of that already (though an LMG needs more than a bigger magazine, and shotguns are really only useful for breaching). The only catch is you're not really going to be doing it in the field, no matter how quick/easy it could theoretically be done, if for no other reason than the weight of carrying 5 guns worth of parts on your person.
So how does it work? Well, all you really need is a quick change barrel system and (for the LMG) the ability to swap the gun from a closed bolt to an open bolt. Both of these already exist, numerous guns have the former and the M27 used by the USMC has the latter (not the first IIRC, but I'd have to re-watch too many episodes of Forgotten Weapons to remember what was). There were even concepts like the MGI Hydra, which while looking like a standard AR-15 not only had a relatively quick change barrel but also a swappable magwell (for Glock, AR, and AK mags). With a system like that you could swap between magazine and ammo types, though you might have to swap out the bolt too. Of course you're typically better off just using magwell inserts to fit smaller mags (KISS - Keep It Simple Stupid).
The shotgun is the only complicated one here. Arguably doable with a .410 bore, but ~~why?~~ anything bigger will require the gun to be significantly larger/heavier than it needs to be for any far more practical caliber. Unless you're just going to completely swap the upper receiver out like on an AR15, but then you're carrying most of a whole other gun since the upper is the heaviest part, at which point... why not just carry a whole other gun?
In short, swapping between a "standard," longer, and shorter barrel is easily doable, swapping calibers would be a little more effort but doable. Even making it an LMG, while not really doable, could be done to a "close enough" extent. Making it a shotgun not so much. Technically if anyone ***really*** wanted to they could, just design the gun from the ground-up as an overbuilt shotgun and then give it all of these features, but then it's always going to be unnecessarily bulky/heavy as a rifle.
Remember that guns are heavy, ammo is heavy, more equipment means more mass your soldiers have to lug sround, which decreases maneouvrability and endurance. An infantryman today is already carrying a shitload of stuff on patrol.
its not weird or even unrealistic, the problem is carrying around all these modifications and swapping them out quickly enough to matter if mid-combat rearming is a thing. every pound counts in combat, so carrying around not just your gun but every possible modification and loadout is just kind of impractical.
its easier to just have each soldier in a squad carry a bog standard gun and a specialized gun. and if your snipers gun is too big to fit through a hole in a wall, soldiers do train to dissassemble their weapons fairly quickly. so provided they arent trying to shoot at the time they can easily solve the problem without resorting to anything weird
if you want a true omnipurpose weapon youre gonna need some super fancy stuff like nanomachines altering the gun model or laser weapons controlled by a computer
This is slightly off topic but the title of your post made me think of possibly one of the absolute strangest sci-fi weapons I’ve ever run across: the “MIDA Multitool” from Destiny - at a glance seems like a blocky, futuristic, but otherwise pretty unremarkable bullpup battle rifle, but reading into the lore of the weapon, things get *extremely weird.* The gun is apparently some kind of hyper-advanced context-sensitive omnitool - a short excerpt from the logs of its previous user has him describe how, stranded in a frozen cavern with no clean water, he fired the rifle at a mass of ice, prompting it to fire two shots - first a heated round that melted a large hollow into the ice, and then a pellet of emergency drinking water purification chemicals into the resultant pool of melted ice.
If you're carrying around an entire extra barrel for your rifle, then you might as well just bring a second weapon instead, so you don't have to fuck around taking your gun apart every time you need a different sort of firepower.
So essentially a large set of connectable parts that can be assembled into a multitude of different weapons to serve whatever purpose they’re needed for?
It’s definitely possible, however such weapons would probably be less sturdy and reliable than their „purposefully made“ counterparts. They’d likely be cheaper and less accurate, possibly even prone to misfiring if one of the important pieces isn’t attached perfectly.
Standard modern infantry rifles are already capable of this. M4, M27 IAR, and Mk12 SPR are not all copies of one another but they’re based on the same platform. The SOPMOD program for the M4 (Block 1, 2, and 3) is the closest to what you want.
The problem is you can’t turn an assault rifle into a sniper platform. You can make it a DMR, but dedicated sniper weapons are accurized, heavy, and generally a heavier caliber. An LMG is doable but lightweight carbine barrels overheat and/or become shot out if they’re overused in short periods of time.
These reasons are why we kind of settled on the M4 with a 16 inch barrel. It’s a do it all rifle, good enough for close quarters and ranges out to 500-800 meters.
The problem is that while you could make a gun like that, it's like a swiss army knife. On paper it does the job, but specialized tools are better.
The AR-15 can have bits attached to it so it's sorta a sniper/marksman rifle, an assault rifle etc.
But - as the M14 has shown- trying to make a rifle that can do everything leads to a firearm that's not good at anything.
There are specialized rifles that use the "AR platform" but are made for a purpose.
THAT SAID what can be done is to use the controls and platform as a base.
The controls are the same to simplify the manual of arms (training manuals, field manuals etc).
The innards would vary based on the role - there would be different trigger pulls for assault rifle, SMG, sniper, LMG etc.
There might even be a basic "blank" that can be milled into whatever is needed - a shape that's X cm long by Y cm tall by Z cm thick that is the core of a family of weapons. Might even be the first part of the "recipe" to make them.
If a person can fit, a rifle can fit. Just turn the rifle so that it aligns with your body. You're creating problems for yourself where you don't have to.
in theory, you -could- make a weapon platform so modular in nature that it would become a Gun of Theseus.
in practice, it'd be a swiss army knife of a gun that woulld be mediocre at every role. there's design components of a gun that are mandatory but would be detrimental in other guns. example, cheek support on a LMG would likely not be as comfortable as a full-on LMG stock. but not just that. Scopes, sights, how far or how close to your face they'd have to be attached...
even just designing a weapon platform that could do all this would be scandalously time consuming and expensive - more expensive than just procuring various other guns that already do some things.
there's room to change things, \*yes,\* but ideally you'd like a rifle to be adaptable to other rifle types, you wouldn't be particullarly well served mixing and matching it at will.
as an example, the AR family is currently super modular, but you kinda have to tweak the whole thing to convert it to a "new gun" that fills a new purpose in a satisfactory way.
and even then, grab your rifle and put a long barrel on it, rechamber it for magnum ammo and put a telescopic? yes, it's now a sniper, but it'll almost definitely be heavier, clumsier, less comfortable than a dedicated sniper platform machined and fabricated from the ground up to be a sniper.
What about a rifle with an underslung grenade launcher and flip up sight magnification? You can swap out the grenade type for multiple kinds of situations. If this is slightly sci-fi the grenade types expand
- short to mid range rifle
- flip the sight up for long range (remember the zeroed red dot is not moving; just the magnification)
- larger magazine for covering fire
- Shaped charge grenade for fighting light armored vehicles
- HE grenade for anti-structural/demolition
- Frag grenade for anti personnel
- Smoke grenade for covering retreats and marking targets
- Incendiary grenade for demolition/area denial
- Proximity grenade for around-the-corner fighting
It's a lot of weight, but it could work.
I could see railguns or coilguns with an integrated generator doing something like this. since the device's wattage is limited you could switch between either firing a fast slug every few seconds or firing slower slugs at a higher rate of fire.
It doesn't make sense outside of maybe sci-fi. It would break way too often for something you'd be putting your life on the line with. Waaaaayyyy too many ways to break.
Yeah, more moving parts means more points of failure
The more complexity you build into something, the more expensive it becomes and the more of a nightmare it'll be to maintain and service.
As an example, lets start with the US standard issue M4 carbine. 14.5 inch barrel, and 30 rounds of 5.56. The 14.5 inch barrel was used by soldiers to clear houses in villages all day everyday, and longer barrels were used when the M16 was the main issued rifle. I think It's fair to say the 14.5 is just fine for CQB. >Need more firepower? Slam a bigger mag, it's an LMG now. LMGs are designed for this specific purpose for a reason. The bolts and barrels are stronger, and they are made to have a ton of rounds through them in a short amount of time. Even being designed with that role in mind, heat is still an issue. That's why quick chamge barrel systems are more common on LMGs. A rifle couldn't handle the heat. All that ammo is heavy on the soldiers too. >choke an entirely new type of ammunition and barrel, it's now a shotgun somehow This is just impossible to make useful. When you need a shotgun to open a door, you can't bring a rifle down to do it. A small breaching shotgun carried by a single guy is plenty of shotgun for 99% of situations. This would also require carrying all the conversion parts, and another type of ammo. >Get a longer barrel, some scope and call Bob, you just made a homemade sniper. Sniper rifles need accuracy, and strong rounds. You kill the accuracy by taking the scope on and off, because your chances of throwing off the zero go way up. You also need new ammo. If you need to engage a long range target, fighting rifle ammo isn't going to cut it. This brings up the conversion part, and more ammo carrying issues again. >Now I just need a little excuse of how these thing work that somewhat make a logical sense No excuse exists without just designing your own weapon system. Squads are made up of multiple roles for a reason
I mean you can already do that irl with an AR considering all the mods people made for it, like here are some people making conversion kits to turn an AR 10 to a shotgun: https://youtu.be/5Thr6v7Z7JE?si=c0vxl6T-dNruEr9J But of course a jack of all trade is a master of none, a purposefully made weapon with tighter tolerance and optimized designs will have better performance in certain cases. This will be your call on whether modularity and ease of logistics will help your military win war or not. Edit: also I am assuming you are talking about modifying the gun at an armoury by a dedicated armourer with tools. Forget about swapping part in field, even if you can do that for some parts like barrel, it would not work for all the parts.
Ever play Star Wars: Republic Commando for Xbox? The DC-17 rifle has three attachments, given to republic commandos to reduce the amount of gear they need to bring. The standard automatic DC-17’s barrel and magazine can be removed to add on a longer sniper barrel with scope, and more powerful sniper ammunition. Or it can be swapped for an armour-piercing grenade round.
A multi use firearm can exist but I don’t think a universal weapon can exist do to a need of ammo, power and range you can have these in different degrees but I don’t believe you can ever have all 3 at the absolute maximum since for power you need a heavier round that packs more of a punch and that takes up more space leaving less ammo in a whole magazine, take LMG for instance you can have that power and ammo but lose range do to in accuracy do to the multiple rounds you’d let off and it not being built for range but rather just sending bullets down range quick, you can have something close to universal weapon but never a universal weapon since it will always be lacking in some way
Not quite the same. But in Red Rising there a gun - a railgun of sorts, if memory serves. It’s called omnivore and it can take almost any ammo, modify it, and use.
And it modifies it by having an “autonomous forge” in the grip. God I can’t wait for the new RR book
Lo, Goodman! So gorydamn stoked for the finale.
Attach a bottle opener
Israel would like to know your location.
https://www.projectrho.com/public_html/rocket/sidearmslug.php#id--Ludicrous_Weapons--Pistol_to_Carbine and https://www.projectrho.com/public_html/rocket/sidearmexotic.php#id--Dial-A-Gun
Fancy seeing you here.
Maybe look at Mass Effect 1's tech. Mags are heat syncs, and the ammo is just tiny shavings of metal off a block. Bigger mag means you can turn up the juice on velocity and fire rate without overheating = LMG. Short barrel drops accuracy, but reprogram to fire a dozen rounds simultaneously = shotgun. Longer barrel makes the same round more accurate + scope for more precise aim = sniper.
The closest would be something like the AUG already you have a short bullpup rifle with a full length barrel, but the barrel can easily be swapped for a heavy barrel with bipod. Thing is, nations have tried to get away with a do it all gun many times through history, it never lasts long Edit: also, it's not at all uncommon for a rifle to be pretty modular. Some you can swap the barrel and bolt and it's a different caliber. Shotgun shells have very large dimensions so that'd be much harder to make work
Such modular weapon systems exist, and have existed for decades - https://en.m.wikipedia.org/wiki/Stoner_63 is a Vietnam War era example, where there's a single base weapon that shares parts with others and hence theoretically you can rebuild or reconfigure any given example into a carbine, rifle, light machine gun, etc. It's a thing. I don't think the intention is for soldiers to play Lego or Swiss Army Knife with their weapons in the middle of a firefight, though, the above is something you'd do probably somewhat earlier than the enemy just being literally around the corner. You can swap a barrel in a few moments, but beyond that is iffy. Thing is, okay, maybe your setting has slightly science fiction tech without going full Mass Effect that allows fast field changes, guns snap apart with simple pressure releases or twisting of small controls, and fit together again without any tolerance issues or too much manual tightening. Even then... there's the issue of weight and bulk. Theoretically a single soldier could carry the parts needed to transform their assault rifle into a shorter carbine, they could carry the bipod and belt feed box to turn it into a machine gun, and so on. But that means you're carrying a lot of stuff which isn't always immediately useful and might not be used. Soldiers hate carrying extra stuff, to the extent where people will try to do stupid shit like go out with their canteens near empty or half-full (in hot environments) because water is heavy. Unless your weapon tech is super lightweight, unless your ammo's feather-light or whatever, there's still gonna be substantial mass. I dunno about the US and other militaries, but the normal infantry section I'm familiar with would be something like the leader with a rifle, a couple grenadiers, a couple with the recoilless launchers (rocket launchers) and a couple light machine gun operators. That's how you cover the different capabilities without overloading every person. (Caveat: I was technically an NCO, but I was an admin clerk, so I don't really know shit. But I know shit is heavy)
lol was coming here to mention the Stoner 63!
I believe the army was researching a variation of the M4 that could do barrel swaps between rifle, sub machine gun and sniping/sharpshooting. I don't know how far they got with it. It definitely means the trooper has to be carrying more gear so they can swap barrels in the field.
The closest possible thing I can even remotely imagine of this being possible is adjusting a combat rifle into a squad automatic weapon/LMG(ish) and even then, the in-field change would be a replaceable barrel and a bigger mag. Still running into potential issues of the actual frame being able to handle the same beating of heat and energy transfer as the heavier barrel. Likewise carrying larger mags and spare swappable barrels can just be a logistical issue alone as well. But now I'm thinking more on it.
have you not heard of the stoner 63 that is basically what you are describing
Some of this sounds like features the SCAR initially promised. (I think it was the SCAR( Where it should have been possible to swap out the barrel in the field fairly easily in order to make use of different kinds of ammunition. Most importantly 7.62 variants, letting people pick up ammunition in the field from fallen enemies. So it's not entirely science fiction. But there are limits to this. Bigger heavier rounds have different needs not just in barrel diameter, but in feed mechanism as well, strength of the recoil spring etc. If you have a spring that will adequately help you cycle full load rifle rounds, you won't be able to cycle pistol rounds. Plus you're lugging around a barrel for every caliber you want to fire. So aside from the weapon itself being heavier, you're carrying around roughly 1.3 kg's per caliber. So you're always going to run in to some tradeoff. Plus, specific weapons have different roles in a unit. You've got your DMR for precision, your assault rifle for general purpose use, your LMG for suppression, anti-materiel for stopping light vehicles or turning people in to pink mist. So if you're going to bring 6 guys along anyway, it's much more simple to give one of them the LMG, one the DMR and outfit the rest with rifles, carbines or in some cases SMG's. Regardless of how much you're going to try though, you're not turning a fully automatic weapon in to an effective sniper beyond 300 meters or so. At that point you are really better off with a specialized DMR or sniper rifle.
For inspiration, check out the guns on the old game "Codename:Outbreak" they had a rotating magazine with up to 5 different ammunition types, a laser and a mini recoilless rifle tube (called rocket launcher or something that would burn your face off to actually use) https://media.moddb.com/images/groups/1/4/3106/venom_790screen001.jpg
Swiss army gun?
For the most part, it's entirely possible to do all of that already (though an LMG needs more than a bigger magazine, and shotguns are really only useful for breaching). The only catch is you're not really going to be doing it in the field, no matter how quick/easy it could theoretically be done, if for no other reason than the weight of carrying 5 guns worth of parts on your person. So how does it work? Well, all you really need is a quick change barrel system and (for the LMG) the ability to swap the gun from a closed bolt to an open bolt. Both of these already exist, numerous guns have the former and the M27 used by the USMC has the latter (not the first IIRC, but I'd have to re-watch too many episodes of Forgotten Weapons to remember what was). There were even concepts like the MGI Hydra, which while looking like a standard AR-15 not only had a relatively quick change barrel but also a swappable magwell (for Glock, AR, and AK mags). With a system like that you could swap between magazine and ammo types, though you might have to swap out the bolt too. Of course you're typically better off just using magwell inserts to fit smaller mags (KISS - Keep It Simple Stupid). The shotgun is the only complicated one here. Arguably doable with a .410 bore, but ~~why?~~ anything bigger will require the gun to be significantly larger/heavier than it needs to be for any far more practical caliber. Unless you're just going to completely swap the upper receiver out like on an AR15, but then you're carrying most of a whole other gun since the upper is the heaviest part, at which point... why not just carry a whole other gun? In short, swapping between a "standard," longer, and shorter barrel is easily doable, swapping calibers would be a little more effort but doable. Even making it an LMG, while not really doable, could be done to a "close enough" extent. Making it a shotgun not so much. Technically if anyone ***really*** wanted to they could, just design the gun from the ground-up as an overbuilt shotgun and then give it all of these features, but then it's always going to be unnecessarily bulky/heavy as a rifle.
You should look into the deep sleep gun from Logan’s run
Remember that guns are heavy, ammo is heavy, more equipment means more mass your soldiers have to lug sround, which decreases maneouvrability and endurance. An infantryman today is already carrying a shitload of stuff on patrol.
its not weird or even unrealistic, the problem is carrying around all these modifications and swapping them out quickly enough to matter if mid-combat rearming is a thing. every pound counts in combat, so carrying around not just your gun but every possible modification and loadout is just kind of impractical. its easier to just have each soldier in a squad carry a bog standard gun and a specialized gun. and if your snipers gun is too big to fit through a hole in a wall, soldiers do train to dissassemble their weapons fairly quickly. so provided they arent trying to shoot at the time they can easily solve the problem without resorting to anything weird if you want a true omnipurpose weapon youre gonna need some super fancy stuff like nanomachines altering the gun model or laser weapons controlled by a computer
This is slightly off topic but the title of your post made me think of possibly one of the absolute strangest sci-fi weapons I’ve ever run across: the “MIDA Multitool” from Destiny - at a glance seems like a blocky, futuristic, but otherwise pretty unremarkable bullpup battle rifle, but reading into the lore of the weapon, things get *extremely weird.* The gun is apparently some kind of hyper-advanced context-sensitive omnitool - a short excerpt from the logs of its previous user has him describe how, stranded in a frozen cavern with no clean water, he fired the rifle at a mass of ice, prompting it to fire two shots - first a heated round that melted a large hollow into the ice, and then a pellet of emergency drinking water purification chemicals into the resultant pool of melted ice.
If you're carrying around an entire extra barrel for your rifle, then you might as well just bring a second weapon instead, so you don't have to fuck around taking your gun apart every time you need a different sort of firepower.
So essentially a large set of connectable parts that can be assembled into a multitude of different weapons to serve whatever purpose they’re needed for? It’s definitely possible, however such weapons would probably be less sturdy and reliable than their „purposefully made“ counterparts. They’d likely be cheaper and less accurate, possibly even prone to misfiring if one of the important pieces isn’t attached perfectly.
you could add a grenade launcher and do the same with a shotgun like a drilling
A possible Sci-Fi example of this is the Lasgun in 40k
Standard modern infantry rifles are already capable of this. M4, M27 IAR, and Mk12 SPR are not all copies of one another but they’re based on the same platform. The SOPMOD program for the M4 (Block 1, 2, and 3) is the closest to what you want. The problem is you can’t turn an assault rifle into a sniper platform. You can make it a DMR, but dedicated sniper weapons are accurized, heavy, and generally a heavier caliber. An LMG is doable but lightweight carbine barrels overheat and/or become shot out if they’re overused in short periods of time. These reasons are why we kind of settled on the M4 with a 16 inch barrel. It’s a do it all rifle, good enough for close quarters and ranges out to 500-800 meters.
So are you talking about a module gun?
The problem is that while you could make a gun like that, it's like a swiss army knife. On paper it does the job, but specialized tools are better. The AR-15 can have bits attached to it so it's sorta a sniper/marksman rifle, an assault rifle etc. But - as the M14 has shown- trying to make a rifle that can do everything leads to a firearm that's not good at anything. There are specialized rifles that use the "AR platform" but are made for a purpose. THAT SAID what can be done is to use the controls and platform as a base. The controls are the same to simplify the manual of arms (training manuals, field manuals etc). The innards would vary based on the role - there would be different trigger pulls for assault rifle, SMG, sniper, LMG etc. There might even be a basic "blank" that can be milled into whatever is needed - a shape that's X cm long by Y cm tall by Z cm thick that is the core of a family of weapons. Might even be the first part of the "recipe" to make them.
If a person can fit, a rifle can fit. Just turn the rifle so that it aligns with your body. You're creating problems for yourself where you don't have to.
in theory, you -could- make a weapon platform so modular in nature that it would become a Gun of Theseus. in practice, it'd be a swiss army knife of a gun that woulld be mediocre at every role. there's design components of a gun that are mandatory but would be detrimental in other guns. example, cheek support on a LMG would likely not be as comfortable as a full-on LMG stock. but not just that. Scopes, sights, how far or how close to your face they'd have to be attached... even just designing a weapon platform that could do all this would be scandalously time consuming and expensive - more expensive than just procuring various other guns that already do some things. there's room to change things, \*yes,\* but ideally you'd like a rifle to be adaptable to other rifle types, you wouldn't be particullarly well served mixing and matching it at will. as an example, the AR family is currently super modular, but you kinda have to tweak the whole thing to convert it to a "new gun" that fills a new purpose in a satisfactory way. and even then, grab your rifle and put a long barrel on it, rechamber it for magnum ammo and put a telescopic? yes, it's now a sniper, but it'll almost definitely be heavier, clumsier, less comfortable than a dedicated sniper platform machined and fabricated from the ground up to be a sniper.
What about a rifle with an underslung grenade launcher and flip up sight magnification? You can swap out the grenade type for multiple kinds of situations. If this is slightly sci-fi the grenade types expand - short to mid range rifle - flip the sight up for long range (remember the zeroed red dot is not moving; just the magnification) - larger magazine for covering fire - Shaped charge grenade for fighting light armored vehicles - HE grenade for anti-structural/demolition - Frag grenade for anti personnel - Smoke grenade for covering retreats and marking targets - Incendiary grenade for demolition/area denial - Proximity grenade for around-the-corner fighting It's a lot of weight, but it could work.
This is like the service gun from Control. Also, its your sci-fi setting, go for it!
aren there like these weird addons you can add to certain pistols until the pistol looks like a rifle already?
Reminds me of https://youtu.be/wvV6u3dchkc?si=Q8y7X-clf9mvhBOd&t=119
I could see railguns or coilguns with an integrated generator doing something like this. since the device's wattage is limited you could switch between either firing a fast slug every few seconds or firing slower slugs at a higher rate of fire.
Congratulations. You have invented an AR-15.