You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Ambidextrious Bullpup
- Thread starter Nightcrawler
- Start date
- Status
-
Not open for further replies.
Cthulhu
Member
Anyone remember the Bushmaster ARM pistol? It handily solved the ambidextrous ejection port issue by having a rear receiver that could pivot left or right, ejecting out of a port that would be exactly opposite of the magazine well. Right handed shooters pivot the magazine well to the left, where it is braced across their arm, and the ejection port is at a 45 degree angle to the right. Left handers have it exactly opposite. The big problems involve running the gas system to the rear, figuring out where to mount the sights, and heat buildup. The ARM was intened as a PDW, so the less than ideal sights were no big issue. Modern materials and heat shielding should be able to mitigate the heat issues for the user. The Gwinn Bushmasters I've seen functioned well enough, but anyone who's seen reliability issues with the rotating reciever please post.
Building this design into a carbine would be a fairly simple feat. Add an indexable buttplate (if necessary). Extend the bbl to move the blast away from the users face and increase terminal ballistics. Add a foregrip/trigger guard ala the P90 or Tavor to facilitate a two hand hold, not to mention serve as a platform for lights, toys, etc. One could mount the front sight on the now extended BBL to improve sight radius, and incorporate apperture sights (though sight adjustments will be a trick). Trigger will still, more than likely, suck.
Building this design into a carbine would be a fairly simple feat. Add an indexable buttplate (if necessary). Extend the bbl to move the blast away from the users face and increase terminal ballistics. Add a foregrip/trigger guard ala the P90 or Tavor to facilitate a two hand hold, not to mention serve as a platform for lights, toys, etc. One could mount the front sight on the now extended BBL to improve sight radius, and incorporate apperture sights (though sight adjustments will be a trick). Trigger will still, more than likely, suck.
My Ideal Bullpup
If I were to design a bullpup from scratch I would design it to NOT EJECT.
I would use casless ammo and have the bolt group integral to the magazine. A recoil delayed blowback setup would be excellent. No ejection port, no dirt getting in my action, no weak feed lips. Just one rugged polymer box magazine with at least 50 rounds of ammo. It would load from the top and double as a cheek piece.
Since the bolt group is removed with every mag change there would be no danger of overheating. Preferably the magazine would be a one-time use disposable package lubed and sealed at the factory. The bolt group then only have to work for a very short operational life, and could thus be made of cast alloy for low cost and lightness. As we don't have brass, further weight saving can be realized.
If I were to design a bullpup from scratch I would design it to NOT EJECT.
I would use casless ammo and have the bolt group integral to the magazine. A recoil delayed blowback setup would be excellent. No ejection port, no dirt getting in my action, no weak feed lips. Just one rugged polymer box magazine with at least 50 rounds of ammo. It would load from the top and double as a cheek piece.
Since the bolt group is removed with every mag change there would be no danger of overheating. Preferably the magazine would be a one-time use disposable package lubed and sealed at the factory. The bolt group then only have to work for a very short operational life, and could thus be made of cast alloy for low cost and lightness. As we don't have brass, further weight saving can be realized.
MrAcheson
Member
Gabe , how do you deal with a misfire? Change bolt and mags? What happens when dirt gets into your perfect sealed magazines (because it still will).
Destructo6
Member
Obviously there would have to be an unloading port. It could be a pretty simple spring-loaded trapdoor, not unlike the M16's ejection port cover, except it would remain closed unless unloading. The caseless G11 had a similar door.Gabe , how do you deal with a misfire? Change bolt and mags? What happens when dirt gets into your perfect sealed magazines (because it still will).
I wouldn't feel comfortable putting my face against a disposeable breech block.
geekWithA.45
Moderator Emeritus
Hmmm...design it to not eject.
Just to follow this thought a little...what if you left a large resevoir in the stock to catch the brass, say, 2 mag's worth, and rig it such that it popped open and dumped the brass all at once when changing mags?
My initial thought would be problems with spent brass clogging, and clearing "normal" jams would be made more difficult by the enclosed mechanism, but since we're thinking outside the box, I figured I'd throw in my .02
Just to follow this thought a little...what if you left a large resevoir in the stock to catch the brass, say, 2 mag's worth, and rig it such that it popped open and dumped the brass all at once when changing mags?
My initial thought would be problems with spent brass clogging, and clearing "normal" jams would be made more difficult by the enclosed mechanism, but since we're thinking outside the box, I figured I'd throw in my .02
Gabe , how do you deal with a misfire? Change bolt and mags? What happens when dirt gets into your perfect sealed magazines (because it still will).
Destructo6 has the answer much along my line of thinking. Simple misfire can be cleared with a special port.
I have a great deal of confidence in modern container sealing technology. Besides it takes quite a bit of dirt to jam the action. With caseless ammo you also need some way to protect the powder. Historically we protected cartridges individually, so why not do it as a package? My proposal isn't technically caseless, the magazine itself *IS* the case.
Think about it, what typically goes wrong in a rifle? It's the magazine and bolt group. By taking these out there's practically nothing that can mechanically go wrong with the rifle itself. If the weapon is FUBARed due to extreme contamination of the magazine, dump the mag and pop in a new one. This must be far more preferable to doing field gunsmithing.
I wouldn't feel comfortable putting my face against a disposeable breech block.
I was thinking we can vent the gases through the unloading port in an emergency. With a disposable kit it should be designed to fail safely instead to withstand failure through over engineering. At least you won't have to worry about stress fracture on your breech block from the weapon's previous users.
Just to follow this thought a little...what if you left a large resevoir in the stock to catch the brass, say, 2 mag's worth, and rig it such that it popped open and dumped the brass all at once when changing mags?
geekWithA.45,
I think your reservior would have to be very large, unless you can store the spent shells in an orderly way. Worth testing though.
Cthulhu
Member
Ooh...Caseless ammo. My tilt receiver suggestion is simple by comparison. The G11 didn't use caseless ammo just to come up with an ambidextrous bullpup, though that was a benefit of the design. The caseless ammo allowed them to achieve a specific design goal, the desired burst firing rate of 1800-2000rpm, by eliminating the extraction and ejection step from the firing system.
By eliminating the case, we of course can eliminate the need for aforementioned operating steps. It does indeed reduce the weight of the ammunition by eliminating the casing weight. Both noteworthy advantages.
However, eliminating the case raises some other issues which, along with the fifty round toploading magazine and expendable bolt group, compound its complexity of the proposed rifle. When you abandon the case, you are also eliminating the seal that prevents the hot firing gases from exiting the rear of the chamber. Now the bolt must obdurate the chamber against 40-60,000 psi of superheated gas with minimal leakage until the pressures have subsided enough to open the action safely.
Heat energy is another huge problem. While the heat evolved during firing is disipated by the metal parts of the bolt, barrel, and receiver, much of it is actually heating the casing which is then flung from the rifle, taking heat with it. Without these little heat sinks, that energy must now be absorbed by the system and be evacuated in the form of hot gas through an exhaust port in the rifle. Said port must now be positioned to clear left and right hand users, so its straight up or straight down. Dumping the bolt every 50 rounds isn't likely to cool the chamber and receiver very much. Accumulated heat will eventually cookoff the rounds, which was a problem that took HK quite a while to beat with the G11.
Unless you want a magazine like a Bren mag, mounted vertically upward, the cartridges will have to sit 90 degrees to the boreline and run along the top. To use a cartridge of any useful OAL, this almost necessitates the same rotary bolt arrangement seen in the G11. HK managed to solve the obduration problem and the vertical feed magazine simply by using a precision engineered (read expensive!) bolt and firing pin/chamber obdurator. The bolt must index nearly perfectly and be strong enough to survive multiple (50) firings with no leakage, yet be cheap enough to just throw away at each mag change. Lets not forget it must be light enough not to cancel the weight savings from eliminating the brass casings. And fifty rounds must fit within the length of the rifle ahead of the breach. That would be easier to achieve with a square or hexagonal cartridge cross section, so there is no wasted space in the mag. Of course, that means that the conventional linear bolt is all but impossible and the rotary design must be used.
The 4.7mmx21 caseless round selected by HK was designed to deliver compact rounds with low recoil, not for their terminal ballistics. They were intended to deliver their wounding effect from 3 rounds hitting in a dispersed pattern, so the relatively anemic round is less of an issue. If you want a .308 or similar caliber bullet at a reasonable velocity, the caseless rounds must carry more propellent. This means a larger in cross section and/or OAL, with the corresponding decrease in magazine capacity. It also means more heat evolved which must be dealt with to avoid cooking off the ammunition.
One could always argue that high volume production techniques can significantly reduce the cost of the replaceable bolt group in terms of machining and (possibly) materials. This is probably true, but it will be a tough sell to anyone but the military, and even then, as seen in the XM8 arguement, the weapon will need to provide an overwhelming improvement in performance to justify its adoption. Then there are logistical problems with replacing ammuntion, not to mention those with the ammunition production itself.
Seems like an awful lot of work and expense to make a rifle shorter. Should they find a way to solve the above problems and make it all work, you are likely to find yourself with a short, handy rifle that is awkward to load and has a lousy trigger.
By eliminating the case, we of course can eliminate the need for aforementioned operating steps. It does indeed reduce the weight of the ammunition by eliminating the casing weight. Both noteworthy advantages.
However, eliminating the case raises some other issues which, along with the fifty round toploading magazine and expendable bolt group, compound its complexity of the proposed rifle. When you abandon the case, you are also eliminating the seal that prevents the hot firing gases from exiting the rear of the chamber. Now the bolt must obdurate the chamber against 40-60,000 psi of superheated gas with minimal leakage until the pressures have subsided enough to open the action safely.
Heat energy is another huge problem. While the heat evolved during firing is disipated by the metal parts of the bolt, barrel, and receiver, much of it is actually heating the casing which is then flung from the rifle, taking heat with it. Without these little heat sinks, that energy must now be absorbed by the system and be evacuated in the form of hot gas through an exhaust port in the rifle. Said port must now be positioned to clear left and right hand users, so its straight up or straight down. Dumping the bolt every 50 rounds isn't likely to cool the chamber and receiver very much. Accumulated heat will eventually cookoff the rounds, which was a problem that took HK quite a while to beat with the G11.
Unless you want a magazine like a Bren mag, mounted vertically upward, the cartridges will have to sit 90 degrees to the boreline and run along the top. To use a cartridge of any useful OAL, this almost necessitates the same rotary bolt arrangement seen in the G11. HK managed to solve the obduration problem and the vertical feed magazine simply by using a precision engineered (read expensive!) bolt and firing pin/chamber obdurator. The bolt must index nearly perfectly and be strong enough to survive multiple (50) firings with no leakage, yet be cheap enough to just throw away at each mag change. Lets not forget it must be light enough not to cancel the weight savings from eliminating the brass casings. And fifty rounds must fit within the length of the rifle ahead of the breach. That would be easier to achieve with a square or hexagonal cartridge cross section, so there is no wasted space in the mag. Of course, that means that the conventional linear bolt is all but impossible and the rotary design must be used.
The 4.7mmx21 caseless round selected by HK was designed to deliver compact rounds with low recoil, not for their terminal ballistics. They were intended to deliver their wounding effect from 3 rounds hitting in a dispersed pattern, so the relatively anemic round is less of an issue. If you want a .308 or similar caliber bullet at a reasonable velocity, the caseless rounds must carry more propellent. This means a larger in cross section and/or OAL, with the corresponding decrease in magazine capacity. It also means more heat evolved which must be dealt with to avoid cooking off the ammunition.
One could always argue that high volume production techniques can significantly reduce the cost of the replaceable bolt group in terms of machining and (possibly) materials. This is probably true, but it will be a tough sell to anyone but the military, and even then, as seen in the XM8 arguement, the weapon will need to provide an overwhelming improvement in performance to justify its adoption. Then there are logistical problems with replacing ammuntion, not to mention those with the ammunition production itself.
Seems like an awful lot of work and expense to make a rifle shorter. Should they find a way to solve the above problems and make it all work, you are likely to find yourself with a short, handy rifle that is awkward to load and has a lousy trigger.
You are reading too much of the G-11 into my idea.
My ideal caseless ammo would be more powerful than 5.56 NATO, yet lighter from lack of brass.
Second I do not like the G-11's magazine and would prefer a four stack box, even a helixical drum is better suited. The G-11's action is indeed too complex and precise, which is why I prefer a more traditional linear bolt group.
The G-11 had overheating problems because it doesn't use a disposable bolt group. Other than the barrel, the breech is where the heat accumulates. How will it overheat when I'm changing the bolt every 50 rounds?
As to breech leakage, it would not lead to MTBF of less than 50 rounds. One problem of caseless ammo in the dozens of rifles designed for them has been the built up of incompeletly burned material in the breech. My solution is simply to tolerate this fouling for 50+ shots, which isn't hard to do. It's trying to do so for 5,000+ that caused previous projects to fail.
The improvement to the M-16 would be potentially greater than the XM8. It would be more powerful, lighter, shorter, more reliable, require less cleaning and armoury maintenence, no time would be wasted loading and unloading magazines. I'm not saying the military would have any interest in such a radical design. But if the need is there, we have the technology to do it.
My ideal caseless ammo would be more powerful than 5.56 NATO, yet lighter from lack of brass.
Second I do not like the G-11's magazine and would prefer a four stack box, even a helixical drum is better suited. The G-11's action is indeed too complex and precise, which is why I prefer a more traditional linear bolt group.
The G-11 had overheating problems because it doesn't use a disposable bolt group. Other than the barrel, the breech is where the heat accumulates. How will it overheat when I'm changing the bolt every 50 rounds?
As to breech leakage, it would not lead to MTBF of less than 50 rounds. One problem of caseless ammo in the dozens of rifles designed for them has been the built up of incompeletly burned material in the breech. My solution is simply to tolerate this fouling for 50+ shots, which isn't hard to do. It's trying to do so for 5,000+ that caused previous projects to fail.
The improvement to the M-16 would be potentially greater than the XM8. It would be more powerful, lighter, shorter, more reliable, require less cleaning and armoury maintenence, no time would be wasted loading and unloading magazines. I'm not saying the military would have any interest in such a radical design. But if the need is there, we have the technology to do it.
corncob
Member
geek,
ejecting the spent cases into the stock still leaves you with the problem of not being able to get into the rifle quickly to clear a jam, etc.
Also, a traditional extractor/ejector setup sets the cases to spinning as they leave the action--if there is anything close for them to collide with the results would be unpredictable.
ejecting the spent cases into the stock still leaves you with the problem of not being able to get into the rifle quickly to clear a jam, etc.
Also, a traditional extractor/ejector setup sets the cases to spinning as they leave the action--if there is anything close for them to collide with the results would be unpredictable.
Cthulhu
Member
I used the G11 as a basis, since it is the only caseless semi-automatic rifle that could possibly be deemed "sucessful." Then I went on to show how caseless designs have problems that the G11 only barely compensated for, and that the proposed rifle, which gave few details as to functioning, magazine design, etc would only aggravate the shortcomings of the basic caseless design.
But given the new specs, I will address them individually. 4 stack box mag?Been done with the Spectre, and they were still large and heavy even with pistol rounds. Needs a large receiver. Feeding can be a nightmare too.
Helixical drum. Work so-so with pistol rounds. Rifle rounds ensure that the drum has a large diameter. More expensive than box mags. Heavier when loaded than chargers or smaller box mags. Must be wound before firing if a clockwork type, or else advanced by the firing mechanism, both which make a tupperware like-seal difficult to achieve.
Breach leakage would definitely lead to at MTBF of less than 50 rounds. Possibly a MRBF of 1. Superheated gas vents from the rear of the breach. Caseless rounds in heavy, vertically mounted magazine have no where to go to escape the rush of the gas. Said rounds ignite.
The linear bolt mechanism does work, so long as the cartridges are presented in the conventional feed position. The Fiocchi/Benelli used the same concept with the caseless 9mm AUPO round in their BM-2 submachine gun, which I'm sure everyone has heard of and lusts after. It used a long bolt with annular rings like a engine piston. The linear bolt also requires an extractor to clear a malfunction, which must work while allowing the bolt to seal effectively.
The whole idea seems to be based on the fact that a linear bolt does not require precision manufacture in order to function well for a short period of time (30 to 50 rounds). While I would bet that I could design an open bolt sub gun that would operate for 50 rounds at cyclic using a non-metallic bolt, that doesn't make it is a good idea, nor guarantee that such a design would be adaptable to closed bolt, delayed blowback arm using rifle cartridges. And the bolt would still require precision manufacture (the main cost, given non-exotic materials) in order to feed smoothly/reliably and facilitate the mechanical delay device. Even the M3 grease gun had a machined bolt (and bbl).
Heat would still be a problem. Changing the bolt will carry away some of the heat, however the barrel and chamber are not replaced with each mag change, nor will they clean themselves.
How about a operator confidence problem? You present the soldier with a rifle that upon each magazine change has a brand new shiny bolt group, lubricated to factory specs, along with a supply of ammunition, protected by an airtight seal. He also has no idea if his newly reloaded weapon will work until he pulls the trigger. Although theoretically weapons can break or malfunction at anytime, the most people feel that if the weapon has been functioning well for XXX number of rounds and is properly maintained they can be confident that it will continue to function. Now here we are hot swapping parts that must work together flawlessly with no fitting or even testing, are made cheaply enough to be disposable, and have an expected average life of exactly one magazine. I don't know about everyone else, but the first thing I do after repairing or replacing parts is to test fire the weapon to check that functioning as close to 100% as I can achieve, in addition to testing magazines and issued/selected ammo.
The technology for caseless rifles has been around for quite sometime. It still may eventually replace case based systems in the future, though we may not be around to see it. I don't see the disposable bolt winning over to many users though. We've learned to operate around the shortcomings of the cased projectile and seem unwilling to adopt new weapons that are equally problamatic.
But given the new specs, I will address them individually. 4 stack box mag?Been done with the Spectre, and they were still large and heavy even with pistol rounds. Needs a large receiver. Feeding can be a nightmare too.
Helixical drum. Work so-so with pistol rounds. Rifle rounds ensure that the drum has a large diameter. More expensive than box mags. Heavier when loaded than chargers or smaller box mags. Must be wound before firing if a clockwork type, or else advanced by the firing mechanism, both which make a tupperware like-seal difficult to achieve.
Breach leakage would definitely lead to at MTBF of less than 50 rounds. Possibly a MRBF of 1. Superheated gas vents from the rear of the breach. Caseless rounds in heavy, vertically mounted magazine have no where to go to escape the rush of the gas. Said rounds ignite.
The linear bolt mechanism does work, so long as the cartridges are presented in the conventional feed position. The Fiocchi/Benelli used the same concept with the caseless 9mm AUPO round in their BM-2 submachine gun, which I'm sure everyone has heard of and lusts after. It used a long bolt with annular rings like a engine piston. The linear bolt also requires an extractor to clear a malfunction, which must work while allowing the bolt to seal effectively.
The whole idea seems to be based on the fact that a linear bolt does not require precision manufacture in order to function well for a short period of time (30 to 50 rounds). While I would bet that I could design an open bolt sub gun that would operate for 50 rounds at cyclic using a non-metallic bolt, that doesn't make it is a good idea, nor guarantee that such a design would be adaptable to closed bolt, delayed blowback arm using rifle cartridges. And the bolt would still require precision manufacture (the main cost, given non-exotic materials) in order to feed smoothly/reliably and facilitate the mechanical delay device. Even the M3 grease gun had a machined bolt (and bbl).
Heat would still be a problem. Changing the bolt will carry away some of the heat, however the barrel and chamber are not replaced with each mag change, nor will they clean themselves.
How about a operator confidence problem? You present the soldier with a rifle that upon each magazine change has a brand new shiny bolt group, lubricated to factory specs, along with a supply of ammunition, protected by an airtight seal. He also has no idea if his newly reloaded weapon will work until he pulls the trigger. Although theoretically weapons can break or malfunction at anytime, the most people feel that if the weapon has been functioning well for XXX number of rounds and is properly maintained they can be confident that it will continue to function. Now here we are hot swapping parts that must work together flawlessly with no fitting or even testing, are made cheaply enough to be disposable, and have an expected average life of exactly one magazine. I don't know about everyone else, but the first thing I do after repairing or replacing parts is to test fire the weapon to check that functioning as close to 100% as I can achieve, in addition to testing magazines and issued/selected ammo.
The technology for caseless rifles has been around for quite sometime. It still may eventually replace case based systems in the future, though we may not be around to see it. I don't see the disposable bolt winning over to many users though. We've learned to operate around the shortcomings of the cased projectile and seem unwilling to adopt new weapons that are equally problamatic.
- Status
-
Not open for further replies.
Similar threads
- Replies
- 25
- Views
- 13K
- Replies
- 1
- Views
- 919
- Replies
- 43
- Views
- 2K
- Replies
- 57
- Views
- 11K