New primary military round will be 6.8 and it will have a plastic case, not brass

Maybe one day us reloaders can make our own “brass” on a 3D printer.

If it works why not?

That case telescoping cartridge is only one of three that might (and it's a very big MIGHT) be the next cartridge for the military. The NGSW programs has been going on for several years now and there are still three different competitor trying to win the contest.



The case telescoping cartridge in the OP post is paired with the Textron system. Sig making there own ammo using a steel/brass hybrid cartridge. General Dynamics has partnered with True Velocity doing a steel/polymer hybrid cartridge.

I think we are still years out from this become reality if it become reality at all.

Don't put too many eggs in this basket just yet. I've been down this road before, several times. Maybe not this exact road, but roads that look a lot like this one. Besides the logistical requirements for such a move (and they are HUGE) this is going to cost some serious $. And I'm not confident that such a large amount of $ is available, or willing to be spent- particularly for a small arms program.

Well, no, it's not.
The new 6.8 is for a support weapon, a SAW (Squad Automatic Weapon), and not the primary ammo. Which is predicted to still be 5.56nato for at least several foreseeable decades.
Journalists have been getting this wrong for nearly five years' now.

Journos have no idea nor notion of how militaries supply ammo, let alone purchase it.

DoD is fielding Cal..50, 7.62nato, and 5.56nato. The 5.56 and 7.62 both in belted and bandoliered fashion, typically stowed in metal cans in wooden crates. So, adding one more caliber, belted into boxes, then into cans and crates is not that much more effort (especially as the 6.8 belted is meant to replace the 5.56 belted ammo 1 for 1).
That latter is driving the use of composite cases--the crates of belted 6.8 are preferred to be not that much heavier than the crates of belted 5.56. The distribution unit is not a box at the range, it's a 20 foot CONEX of crates.

Now, will the ammo makers embrace telescoped rounds, or composite cases? Maybe.
Will that filter out into the civilian ammunition market? Maybe.

Military ammo is made by the billion; most civilian ammo in the millions. That's part of what has caused our recent ammo drought--"we" were able to buy up the standing inventory faster than it could be restocked.

I thought Dardick Tround pistols and GyroJet rifles were the wave of the future. What happened?

CapnMac said:

Journalists have been getting this wrong for nearly five years' now.

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Only 5 years? I could have sworn it has been longer than that.

Pentagon big wigs get their pet projects pushed through all the time. 500 of this, 1000 of that. Keeps the pentagon/industry bed warm.
Changing the military or NATO standard cartridge is another thing entirely. We’ve seen the replacement for 5.56 how many times??
Wasn’t it not long ago the 6.8 SPC was the be-all, end-all of small arms?
Caseless ammo has been around, and failing, for at least 6 decades.

No the NGSW program will replace both the M4/M16 and the M249 SAW if the program is accepted. That is why in the picture I posted above each company competing for the contract is proposing two weapons (except GD that thinks they can do both roles with one weapon). The winner will be supply two weapon to replace the M4/M16 and the M249 and they will both run the same 6.8mm ammo.

Nah, it'd cut into the hunt fer' the boogie-man budget...

Non-metallic cases have a very real thermodynamic hurdle to overcome in terms of heat management. Brass cases remove a LOT of heat energy from the system, as anyone who has ever had a casing go down their shirt knows well.

Polymer cases won’t remove nearly as much heat, requiring either reduced firing rates or some sort of new cooling technology. Or cooler burning propellants.

All based off the LSAT springboard pre 2010 IIRC. It's been a long running effort and even included shuttle bolt operation to seal the chamber as there was no "case" per se to do that. Looks like they have gravitated back to some kind of chamber sealing case. It's less a telescoped round as one with straight walls, more shotgun tech.

The idea is to put a larger weight round out the pipe, the larger diameter base absorbs force more readily than small base, it achieves 3,000fps +++ and has extended range. Not quite the more limited invention of SPC or SOCOM, more along the lines of .308 effective range. Having less weight in the ammo means AS USUAL the soldier carries even more, and the cases were originally not meant to be recovered or recycled. Pump and dump. I dont see that happening as much now. It would mean a crunchy range within a month and garrison Army even paints rock edging so ammo police call after a range exercise and turning in all the residue will go on. Maybe forever. We will be weighing cardboard packing to meet some ridiculous standard to prove it was all shot and not taken home. How's that worked in the past . . . ?

It can and will impact scrap sales of casings, will they be economically unreloadabl? Further, don't be surprised there is a Diktat stating "illegal for civilian use." Based on Government ownership of the technical data, where have we heard that before? Like the Form 4999, be prepared to brace the storm of not getting to use a military cartridge any more. Plan for the worst expect the best. If it's controlled proprietary it will also be ITAR and allies won't get much of it, meaning no surplus battle packs in ten years or imports. Ask all the .30-06 and .308 shooters what the salad days of the 80's/90s were like compared to now. Not so much anymore, a lot have to shoot commercial or reload. That is an unspoken reason for the popularity of 5.56, and we may run thru it again, shooting up a millions of rounds with no future resupply. I guess there will always be Tula. I guess.

A new telescoped case issue round will be another decade down the road. It's fun to speculate keeping in mind that third generation B52 pilots are scratching their name next to Dad's and Granpa's on airframe struts.

Elkins45 said:

Non-metallic cases have a very real thermodynamic hurdle to overcome in terms of heat management. Brass cases remove a LOT of heat energy from the system, as anyone who has ever had a casing go down their shirt knows well.

Polymer cases won’t remove nearly as much heat, requiring either reduced firing rates or some sort of new cooling technology. Or cooler burning propellants.

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I have always wondered about that. Brass is a fairly good conductor of heat and absorbs an amount of the intense heat present during firing. If whatever the cartridge case is made of is a material that doesn't obsorb heat as readily it won;t get as hot and the heat will go down the barrel with the gasses. And maybe even provide some insulation for passing heat to the chamber. Or at least that is a theory that makes sense to me. I would be interested in the actual research on this.

Elkins45 said:

Non-metallic cases have a very real thermodynamic hurdle to overcome in terms of heat management. Brass cases remove a LOT of heat energy from the system, as anyone who has ever had a casing go down their shirt knows well.

Polymer cases won’t remove nearly as much heat, requiring either reduced firing rates or some sort of new cooling technology. Or cooler burning propellants.

Click to expand...

Just the opposite it true and it is one of the advantages of polymer cases. Polymers are almost always an insulator and will insulate the chamber area from the high heat of combustion gases reducing the amount of heat transferred into the barrel.

I think mcb is probably right.

Heat carried off by brass, bullets, and propellant gasses is "robbed" from propulsion. An insulating case should get you more MV for the same pressure. How much more? Heckifino.

mcb said:

Just the opposite it true and it is one of the advantages of polymer cases. Polymers are almost always an insulator and will insulate the chamber area from the high heat of combustion gases reducing the amount of heat transferred into the barrel.

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How are the polymers when it comes to expansion and contraction ? Brass expands to seal the chamber then contracts to be extracted. I also see no extraction rim. Seems like some interesting tech will have to be developed. Then again I am old school, so perhaps that has already been taken care of. Then the 30 percent lighter weapon system, . I can see the use of polymers to accomplish that. The whole thing sounds interesting. A modern day Red Rider. I hope they work out the bugs before it goes afield . The first M16 system got people killed.

What happened to the Sig 6.8mm round AKA .277 Fury???????

https://www.thehighroad.org/index.p...-m4-with-the-ngsw-6-8mm.888311/#post-11920429

The report linked in the OP is from 2020.

mnrivrat said:

How are the polymers when it comes to expansion and contraction ? Brass expands to seal the chamber then contracts to be extracted. I also see no extraction rim. Seems like some interesting tech will have to be developed. Then again I am old school, so perhaps that has already been taken care of. Then the 30 percent lighter weapon system, . I can see the use of polymers to accomplish that. The whole thing sounds interesting. A modern day Red Rider. I hope they work out the bugs before it goes afield . The first M16 system got people killed.

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So with the Case Telescoping round in the OP you do not extract them you push them out the front of a reciprocating chamber (side to side not forward/back) with the next round to be fired. This is one of the supposed advantages, to extraction, just pushing.



Notice how far forward the ejection ports are on these weapons. That is because ejection happens out the front of the reciprocating chamber.

12Bravo20 said:

What happened to the Sig 6.8mm round AKA .277 Fury???????

https://www.thehighroad.org/index.p...-m4-with-the-ngsw-6-8mm.888311/#post-11920429

The report linked in the OP is from 2020.

Click to expand...

They are still in the running.

ETA:

This would be the M4 replacement if the Textron system is selected.

https://twitter.com/i/status/1194136894654894083

Its a twitter link so I can directly embed the video but its a nice cutaway animation of the Textron cycling case telescoping rounds.

I see that the rounds in the mag are pushed out into the reciprocating chamber and this pushes the spent casing out of the chamber at the same time. The reciprocating chamber then moves up to the barrel and the firing pin fires the round. The gas forces the reciprocating chamber down and the recoil spring pushes another round from the mag into the chamber again.

I can see how it works, but it seems this would result in a dirty chamber very quickly. I would think the chamber would need to seal the barrel and the breech end very tightly to work efficiently. I think that could jam up pretty quick. I guess they will use cleaner powder or something? Or maybe the polymer case would be sealed so tight in the chamber and barrel that most of the propellant residue would go down the barrel?

And I am one who would think the heat would all go into the barrel and your gun would heat up faster than a conventional gun. I see that as a major issue.

BigAlShooter said:

I see that the rounds in the mag are pushed out into the reciprocating chamber and this pushes the spent casing out of the chamber at the same time. The reciprocating chamber then moves up to the barrel and the firing pin fires the round. The gas forces the reciprocating chamber down and the recoil spring pushes another round from the mag into the chamber again.

I can see how it works, but it seems this would result in a dirty chamber very quickly. I would think the chamber would need to seal the barrel and the breech end very tightly to work efficiently. I think that could jam up pretty quick. I guess they will use cleaner powder or something? Or maybe the polymer case would be sealed so tight in the chamber and barrel that most of the propellant residue would go down the barrel?

And I am one who would think the heat would all go into the barrel and your gun would heat up faster than a conventional gun. I see that as a major issue.

Click to expand...

The chamber never sees exposure to the combustion gases. The case is sealed at the back end just like a conventional case. The mouth of the case telescoping case seals against the face of the barrel when fired. The chamber remains clean, never directly exposed to combustion gases.

Again the polymer case actually takes more heat away from the system when firing than a brass case does. Polymers have specific heats (capacity to hold thermal energy) that is 2-3 times higher than brass and conversely it his a much lower thermal conductivity. This combination means a polymer case can soak up more thermal energy from the extremely hot propellent gases and due to their lower thermal conductivity will transfer less of it to the chamber in the time it take to eject the spent cartridge.

The key phrase is “in the future”. It’s not a new idea, in the ‘80’s plastic cased ammunition actually made it to a gun store near me. It required a special healed bullet to “snap” into the case to help with neck tension issues and could be reloaded with a simple hand tool. It flopped.



Around 2010 a friend showed up with some ammunition that was going to be the next big thing once it passed military testing, a hybrid brass/plastic case. He gave me the better part of 1000 rounds because, using standard bullets, it lacked sufficient neck tension to function and stay together in AR rifles and he knew I had single shot .223’s. It wasn’t even worth shooting in them and I gave them to another friend myself, only keeping a few examples.



In some rifles they would plink along OK, some they would run OK but if one attempted to unload the bullet would be pulled from the case, staying in the bore and dumping powder in the action. Others had chambers that were not smooth enough and would shred the cases upon extraction.



Someday I think they will get there but I haven’t seen sufficient evidence that goal has been reached yet.

mcb said:

Just the opposite it true and it is one of the advantages of polymer cases. Polymers are almost always an insulator and will insulate the chamber area from the high heat of combustion gases reducing the amount of heat transferred into the barrel.

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Any energy not absorbed by the case has 16+ inches of bore surface to transfer to the barrel before its blown out the muzzle. A polymer case would only insulate the chamber at the expense of increased energy in the rest of the system.

Polymers have specific heats (capacity to hold thermal energy) that is 2-3 times higher than brass and conversely it his a much lower thermal conductivity

Click to expand...

Transfer rates would be extremely important. How fast does that energy soak into the polymer? I’m not entirely convinced there would be a net increase in cooling.

Elkins45 said:

Any energy not absorbed by the case has 16+ inches of bore surface to transfer to the barrel before its blown out the muzzle. A polymer case would only insulate the chamber at the expense of increased energy in the rest of the system.



Transfer rates would be extremely important. How fast does that energy soak into the polymer? I’m not entirely convinced there would be a net increase in cooling.

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The testing Textron and True Velocity has done along with several off their failed processors saw this thermal benefit to polymer cases. The military has funded polymer case projects going back into the 90's and claimed thermal benefits back then too. I don't think it's a huge benefit but all evidence points to the idea it does have a measurable effect to the good side on heat management.