This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.
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rounds like the 224valkyrie which have a nice long ogive, suffer from a fat case, limiting capacity. (for military use)
i dont know if case telescoped would allow very conical bullets like the 545/39 or the valkyrie.
would it be possible to have a squared cartridge which is more space efficient in a double stack mag...
or, have a completely flat shoulder, which can thus be taller, allowing you to slim the case. I heard that flat shoulders don't work with high pressure rounds? could that be solved..
next idea is a semi caseless, where the case contains a solid block of proppellant, but it has no shoulder or neck.....the powder is exposed. this solves the cook off propblem because the case ejects and takes the heat with it. Yet it saves weight and allows that flat shoulder.
last idea is removing the rim and having a ring primer around the case. this saves length, allowing a slimmer case.
some of these ideas would be easier if you had a downward ejecting method like some bullpups. This bypasses the need to 'throw' the case out.
1. The lwrc 6.8 receiver sets mostly solve this
2. With the way modern CT is done very long ogive bullets will require a fatter case or a sabot and there's kinda no way to get around this.
3. No square cartridges aren't a good idea because cartridge cases are pressure bearing vessels. Cylindrical cases just work far better and will be inherently capable of bearing far more pressure for a given wall and base thickness/case weight/case capacity because that's just how geometry and materials science works.
4. Neckless is as close to a flat shoulder as you're going to get again because of geometry and materials science works.
5. This is essentially a reverse benelli cb-m2 which not only wouldn't solve the heat problem but you'd also be eroding the shit out of the chamber and barrel throat with every shot which is in all honesty the absolute worst of all worlds. (Side note: you seem to be extremely confused about how heat transfer works, why it happens, and etc. A lot of your ideas are based in a very fundamental misunderstanding of how heat transfer works and what you can do to mitigate it. In your last series of questions you mentioned sabots somehow preventing heat transfer which they also don't do. It would probably be best to look further into heat transfer and how/where it happens in firearms so that you can answer some of these questions yourself.)
6. Steyr played with a ring primer and no cartridge rim in their ACR entry and they pose unique issues of their own. Also it doesn't really save enough length to matter nor does it really meaningfully allow cartridges to be slimmer. Removing the rim also poses unique and unfun challenges to managing extraction, ejection, and etc disproportionate to any weight or other savings it may grant. This was true even before modern lightweight cartridge case technologies existed and even moreso now. Put simply we've found a variety of ways to reduce the weight of the cartridge base and rim suited to different applications which don't force you into the trade-offs a purely rimless case does. There's also micro primers that can be used in stuff like hk's 4.6 mp7 round where overall case diameter is critical.
Finally downward ejecting bullpups don't bypass the need to throw the case out and more importantly bypassing the need for an ejection stage creates massive problems of it's own because you can't actually bypass that. You will always have a need to get duds/misfires etc out as well as the ability to clear a chambered round without firing it.
You can't get away with completely removing the extraction and ejection steps and quite honestly the current solutions for handling these things are about as good as it gets.
There's also the whole design to fail gracefully principle in firearms which includes the need to engineer for when things go catastrophically wrong such as a cartridge detonation.
If you eliminate the things you want to eliminate you're stuck with finding some way to make the entire gun casing strong enough to withstand a cartridge detonation in order to either absorb the whole explosive force or vector it forward out of the gun so it doesn't injure or kill the user.
In conventional firearms with at least minimally conventional layouts you conveniently have an ejection port and downward through the magazine well to vent the hot gases and etc through to keep it away from the person holding the gun.
I understand that you're trying to figure this stuff out but I think I speak for several people here when I say we'd appreciate you taking more time to think and reason things out as well as looking for some of these answers on your own which are quite easy to find.
Could 5.56 COAL be stretched to something like 7.62x51 levels to allow room for a VLD bullet and higher case capacity while maintaining case diameter for stacking in magazines and belt boxes?
Well, some people have loaded VLD bullets to longer than mag length in .223 Remington.
And the 5.6x50 Magnum cartridge has a case length 5mm longer than 5.56 NATO.
Seems like what you propose should be quite possible.
I believe it's possible but I'm not sure how well it would work.
You could probably do a neckless TV style VLD that wasn't a bit longer than 5.56 coal restriction length and get about all the performance you want though if you're not afraid to push the pressures up and get the performance you want too though.
And if you go that route, at most you need to redesign the bolt and extension to handle the higher pressure.
Realistically if you're trying to do something you can't do that way you're better off increasing bullet diameter.
If you REALLY want to get crazy though you can just sabot that vld and then you're really cooking.
the CT or neckless really interests me, all i've seen is the 6.8 CT, but also an FN experimental 3.5mm CT with 9mm case.
scroll to the bottom and theres a diagram of this round. it looks identical to the 6.8CT.
i was thinking you could maybe avoid the fancy moving chamber rifles, if you had the bullet very slightly exposed?
i dont know what the two 'surrounding' parts are at the top of the round. the two walls around the bullet.
6.8CT has them too. surely a neckless cartridge is lighter because it removes this part.
perhaps you could have a normal shaped round but 'inverse' the neck, so it points downwards. this lets you seat your VLD very deeply.
So reverse neckless is essentially what modern CT is.
In historical CT ammunition the powder was packed up and around the deeply seated projectile pretty close to all the way to the nose cap.
Now though the powder isn't packed nearly as far up and realistically is sorta similar to "uncircumcised neckless" (my apologies for the crass description but it's the best way I can think of to describe it)
Honestly a case could be made for pursuing either ct or neckless going forward and it's kinda down to which one you can make a better gun for at this point.
if you did a cutaway of the NGSW neckless cartridge, what would it look like. would it basically have a reverse neck like i described,....would it need reinforcing and padding out, due to being neckless.
also i heard they used solid propellant like caseless, to better secure the bullet....
The "reverse neck" section of the CT rounds is needed to keep adequate alignment with the bore for the considerable distance that bullet must travel before it is supported by the barrel. In the example you provided, the reverse neck is slightly longer than the ogive and could be considered wasted space since it provides no additional propellant capacity. With the neckless designs I have seen, the ogive extends beyond the cartridge case and into the barrel. It is also possible for some of the full-diameter shank to extend beyond the case so it is almost immediately supported and aligned by the freebore of the barrel. The shoulder section of the case can be solid and just long enough to provide the proper retention of the bullet. The solid section of polymer that holds the bullet might be considered a "reverse neck", although it is unclear if this is what you mean.
For a neckless cartridge where the case diameter is significantly larger than the bullet diameter, I doubt that a tubular "reverse neck" of polymer extending inside the case would be effective. The pressure and flow of the propellant would tend to collapse the tube and send it down the barrel. By a tubular reverse neck, I mean a case which essentially looks like a standard one with the neck folded back inside the shoulder. This means that propellant would be in the annular space between the neck and the case body.
Nincomp explained the "reverse neck" situation with the TV cases better than I probably could have and it matches what I know about the construction.
As far as solid propellant bricks go... No they don't use those in neckless or even CT because they are emphatically a bad idea!
In order to control burn rate and pressure curve you need individual grains with very controlled shaping surface area and size to the point where St Marks (the people who developed the m855a1 and m80a1 powders) has a process for micro stamping dice like indentations in individual powder grains.
From there though cartridges like m855a1 and 6.8 true velocity etc can be loaded to "greater than 100% fill density" which essentially means that you are to an extent compressing the loose individual grains inside the case which will also help stabilize the shank and tail of the projectile that goes down inside the case body/neck.
Using this method you can go to something like 150% fill density if I recall correctly while maintaining the individual micro contoured powder grains that precisely control burn rate and peak pressure which is the secret to getting high velocity out of short barrels without being destructive to the gun.
Going this route makes you come up to your peak operating pressure spec sooner in the firing cycle and stay at that peak operating pressure spec for longer thereby imparting more force and velocity to your projectile more quickly and efficiently.
Combining this greater than 100% fill density and micro contoured powder grains with the neckless TV style case which already gives you an extra few percent burn efficiency in many cases cancels out the loss of volume from the thicker polymer case walls allowing you to achieve the same velocities with physically less powder.
This works well in rifle cases but for pistol cases it doesn't work out as well and you would likely lose performance going to a TV style case while staying within established pressure and etc limits.
Hopefully this helps