Thoughts? I wonder if it will be reloadable.
https://www.americanrifleman.org/content/saami-certifies-first-composite-cased-round/
https://www.americanrifleman.org/content/saami-certifies-first-composite-cased-round/
Composite cartridges?
- Thread starter ImYourHuckleberry
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well, i always enjoy an experiment.
you never know. it might be the future, like LED light bulbs.
might need some adjustment, just as ceramic knives.
might fail, too. remember Remington's ETronX?
you never know. it might be the future, like LED light bulbs.
might need some adjustment, just as ceramic knives.
might fail, too. remember Remington's ETronX?
I doubt it will be, I’d assume the polymer breaks down after one or two firings.
The 308 is boxer primed.
www.tvammo.com
The 308 is boxer primed.
Calibers — True Velocity
www.tvammo.com
The only ammo that is going sell in any real quanitity will be the cheapest ammo so unless they can beat the price on brass it will remain in the exotic range.
surgicaltool
Well-Known Member
I agree; save me some money and we'll talk...
Fess
Well-Known Member
True Velocity claims that their ammo can be made for less money, once production volume picks up. It they can do that, they will probably sell quite a lot, but it may take a while to get to that point. I doubt that it will be reloadable. At this point, the main advantage is lighter weight, something that is mainly important to the military.
Are they claiming it expands to fill/seal the chamber, even briefly? I wonder if it's "dirtier," like steel case, because of relative expansion/springback. If using it results in more buildup/fouling in direct impingment firearms, and that increases failures and/or increased maintainence schedules, does carrying more actually result in greater firepower per troop or unit?
Assuming their composite material is a plastic of somekind, then it almost surely could be made cheaper than any metal case. OTOH, if they're pushing "lightweight" and seeking gov't contracts, then the cost of case production is irrelevant - they'll seek a supply contract based on its "advantages over conventional ammunition" and laugh all the way to the ... oh, wait. They're doing away with banks. ...all the way to the digidollar VR spreadsheet app.
Assuming their composite material is a plastic of somekind, then it almost surely could be made cheaper than any metal case. OTOH, if they're pushing "lightweight" and seeking gov't contracts, then the cost of case production is irrelevant - they'll seek a supply contract based on its "advantages over conventional ammunition" and laugh all the way to the ... oh, wait. They're doing away with banks. ...all the way to the digidollar VR spreadsheet app.
Philosofarmer
Well-Known Member
There has always been an advantage to brass in that you could take brass fireformed in you specific chamber in precision bolt guns and only neck size your reloads. But my understanding of the major advantage in composites, and why the military is adopting the composite in their new machine guns is that they allow guns like the bravo to run cooler. Composites are in essence a heat insulator for the chamber and barrel. The 6.8 they have adopted gives down range ballstic performance will a simple barrel swap.
www.guns.com
True Velocity's 6.8mm Polymer Cased Round Primed for Wider Use :: Guns.com
The hybrid polymer-cased cartridge, developed by Texas-based True Velocity as part of the Army's Next Generation Squad Weapon program, is compatible with legacy firearms as well.
www.guns.com
$3.50 a round is steep. I just can not justify it when brass/reloadable ammunitions can be had or a third the price. I get that it makes sense for the military and they can buy enough to drive the price down, when they do I may try a box.
And since price is irrelevant in their world, it's all good news if it works.
Plus a lot of the terrorist groups around the world that the US gives equipment to are pretty skinny little dudes with poor nutrition, so lightening the loadout is fairly important going forward.
The advantage they will have is set a market price and drive down to that price. This is what a government contract does for a company like them. The ability to buy futures in the supply chain will help alot and I hope this goes forward. Because the metal part of the case is magnetic and I hate picking up brass...
As far as dirty or not, it will only matter if two things have ot happen.
1. Cleaner powder
2. Fluted chambers
I could see where a fluted chamber "could" do wonders for these rounds in the extraction and reliability.
As far as dirty or not, it will only matter if two things have ot happen.
1. Cleaner powder
2. Fluted chambers
I could see where a fluted chamber "could" do wonders for these rounds in the extraction and reliability.
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Fess
Well-Known Member
From what is publicly available, the US Military has yet to choose a 6.8mm cartridge. The advertising from True Velocity and SIG has been confusing, but the fine print actually says that the cartridges were adopted for the trials, not full scale military use. From what I have read there have been enough issues with both the polymer 6.8 TVCM and SIG's 6.8mm hybrid that there is no clear winner. There were some accuracy issues with the polymer round and the bullpup rifle submitted with it was not well liked. The polymer round should be lighter and cheaper than either brass or the hybrid brass/steel case if high production levels are ever reached.
As noted above, the polymer cartridge was submitted with a bullpup rifle. The bullpup's long barrel was needed to get the specified velocity since the polymer round runs at lower pressures than the other two contenders. The lower pressure is what makes it possible to retrofit to old weapon systems, though. The range and energy advantage over 7.62 NATO largely come from the sleek, high BC bullets that were used. Although the goal was reduced weight, the lower heat transfer to a the chamber is an added bonus. A True Velocity spokesman stated that he saw NGSW trials as an ammo program, not a weapons program. It looks like SIG put more effort into the weapons because its cartridge runs at significantly higher pressures.
The front of the TVCM cartridge is some kind of plastic and it indeed does deform and expand during firing. I have not read anything that discusses the amount of case blowby or amount of crud it blows into the action.
But...but...but...
"True Velocity will offer special ammunition subscriptions to customers who purchase these 6.8 mm TVC rifles and conversion kits, providing a discount off retail price and direct-to-consumer delivery."
Hey John, serious question because I don't know: are the advantages of the fluted chamber
a) it provides adequate support for the pressure while reducing the surface area contacting the case;
b) the flutes provide a space for fouling to go so that it doesn't build up on the contact surfaces (chamber wall & cartridge case) to jam up the action?
Fess
Well-Known Member
I am not John, but the short answer is that it makes case extraction easier and prevents the extractor from ripping the rim off or just slipping off the rim.
Longer answer: With a regular chamber, the pressure from firing causes the case briefly to expand and press against the chamber walls. With most gas-operated actions, there is enough delay between firing and extraction that the chamber pressure has time to drop and the friction between the case and chamber walls is reduced enough that the case can slide backwards relatively easily. When people talk about getting the "timing" right on an AR15, they are talking about getting this delay right.
With some other types of action, like delayed blowback, the case begins moving back earlier, while the chamber pressure is high enough that the case is still pressed hard against the chamber wall. This can result in the extractor tearing the rim or the case. Sometimes, the extractor just slips off the rim.
The flutes cut into the chamber gives paths for some of the high-pressure gas to get between the chamber wall and the case, equalizing the pressure on the case walls somewhat and keeping the case from being pressed as hard against the chamber wall and sticking.
Correct,
And thank you @Fess for getting a great answer to the question.
The flutes also act as the "fingers" to allow gas pressure trapped between the bullets heal and the case to push the case out before the case shrinks. this causes a higher rate of fire. Never forget, when the primer goes BANG, the powder goes BOOM and the brass expands to fit the chamber BEFORE the bullet goes to flight. During the whole time of bullet travel within the barrel, the case is at full expansion. IE as reloaders call it, fireformed. This is why you can full length case sizing die brass for reloaders. Flutes allow the extraction to happen while the brass is in its "expansion" mode. Typically because the gas system of the firearm is not able to accomplish this task by its self.
Example1 MP5 Brass 9mm
Example 2 FAL brass 7.62x51mm
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