Poly Ammo! .... ?Maybe

[Viking]

Fairly certain that ARDEC rejected the PPS(polyphenylene sulfide)/PAS(polyarylsulfone)/PPO(polyphenylene oxide)/PAC(polyarylcarbonate) alloys used in the True Velocity cartridge case back in 2005 due to high and low temperature performance deficits. This is why ARDEC launched the CTSAS program. See Chung and Sadowski, ADA 434658, Alternative Case Materials and Design:

http://www.dtic.mil/get-tr-doc/pdf?AD=ADA434658

The True Velocity PPS/PAS/PPO/PAC alloy case may work well in civilian arms under mild conditions, but lacks sufficient high temperature strength to meet military requirements in conventional chambered barrels in closed bolt firing weapons.

See prev comment about mk48, m134, while I don’t think it’s perfected, it’s possible they’ve made serious strides against the failed attempts of the past, then again it could be a lot of hype. Many of the full auto are open bolt for just that reason of cooking off rounds... despite their other problems.

[Ol` Joe]

See prev comment about mk48, m134, while I don’t think it’s perfected, it’s possible they’ve made serious strides against the failed attempts of the past, then again it could be a lot of hype. Many of the full auto are open bolt for just that reason of cooking off rounds... despite their other problems.

There is a article in the July/Aug issue of Rifleshooter on telescoping ammo and the progress being made. The barrels and chambers of some of the test firearms are separate which keeps chamber temps down just for this reason.

[10x25mm]

Polymer cartridge cases - CT or regular - require the separate chamber revolver gun design because the only reliable means of polymer case extraction is a knock out rod.

The only high performance technical polymer family which can resist the long term chemical attack of smokeless powder constituents are PPS/PAS/PPO/PAC alloys. Even the thermosets deteriorate when exposed to smokeless powder. It took years to develop polyethylenes (PE) which could resist the long term chemical attack of smokeless powder constituents in packaging; why steel cans were used so long in the age of plastic. Unfortunately, PEs do not have sufficient strength for high pressure cartridge cases. They do work in shotshell cases.

The PPS/PAS/PPO/PAC alloys have sufficient heat resistance to perform in separate chamber revolver gun designs, but not enough to tolerate reciprocating operation in conventional chambered barrels. ARDEC requires 200 C temperature operation capability in revolvers, but 250 C temperature operation capability in reciprocating operation conventional chambered barrels. The PPS/PAS/PPO/PAC alloys just barely meet the 200 C temperature operation capability, but fall well short of the 250 C temperature operation capability.

The ARDEC CTSAS CT PPS/PAS/PPO/PAC alloy polymer cartridge case design is the only polymer case ammunition which has been TRL 7 (Technology Readiness Level) certified: ready to adopt. Nothing else is so proven.

[Jackam]

I fired polymer cased .308 rounds at the SHOTShow a few years back. They only let us shoot 5 at time (which is normal for every vendor) but I'm quite sure it was through a semi-auto firearm. No problems cycling or extracting. I'll look for pics.

[Ol` Joe]

According to the above mentioned article the military has a light machine gun in development that feeds straight walled telescoping ammo into the chamber which pushes the spent round out ahead of it and has been found reliable to the tune of 85K rds being fired to date in 10 different samples of the gun. The article doesn't expand on whether or not this figure is from each gun the total fired in all be sounds like each the way I read it. This type of action has no timing issues, eliminates rim problems, reduces weight, and the chamber never gets hot enough to cause cook offs.
The work on these has now expanded into carbines and other caliber cartridges, it is not however past any but the early stages of development. You wont see it in the hands of troops anytime soon.

[10x25mm]

According to the above mentioned article the military has a light machine gun in development that feeds straight walled telescoping ammo into the chamber which pushes the spent round out ahead of it and has been found reliable to the tune of 85K rds being fired to date in 10 different samples of the gun. The article doesn't expand on whether or not this figure is from each gun the total fired in all be sounds like each the way I read it. This type of action has no timing issues, eliminates rim problems, reduces weight, and the chamber never gets hot enough to cause cook offs.
The work on these has now expanded into carbines and other caliber cartridges, it is not however past any but the early stages of development. You wont see it in the hands of troops anytime soon.

The CTSAS magazine fed carbine design for CT cartridges is not going well, but this is not the major impediment to adopting the polymer CT ammunition. Textron has proposed a belt feed carbine as a work around and this appears feasible, maybe even desirable.

The actual impediment is a raging debate over the armor penetrating power required in the next generation cartridge. The Army’s other active small arms development program, the Next Generation Weapons System (NGWS) program, proposes a massive increase in chamber pressure to improve armor penetrating power which is well beyond the capabilities of the CTSAS polymer CT cartridge case. At their higher end, the proposed NGWS chamber pressures even exceed the capabilities of CDA 260 brass cartridge cases (about 70,000 psi piezo).

A recent article in Task & Purpose lays out the NGWS program status:

https://taskandpurpose.com/army-next...-squad-weapon/

The Army Says Its Next-Generation Assault Rifle Will Pack A Punch Like A Tank’s Main Gun
By Jared Keller - February 27, 2018

The Army claims its new assault rifle will unleash a hailstorm of specially-designed shells with as much chamber pressure as a battle tank to tear through even the most advanced body armor — and if all goes according to plan, the soldiers will get them to play with sooner than they thought.

The service plans on fielding a Next Generation Squad Automatic Rifle (NGSAR) — the first version in the Army’s Next-Generation Weapons System that chambers a round between 6.5mm and 6.8mm — as a potential replacement for its 80,000 M249 SAWs starting in fiscal 2022 rather than the original target date of fiscal 2025, Col. Geoffrey A. Norman, force development division chief at Army HQ, told Task & Purpose, with two per nine-man infantry squad.

While the service still hasn’t set official requirements for the system, the NGSAR will weigh less, shoot farther, and pack more punch than the service’s existing infantry weapons, Norman told Task & Purpose. And more importantly, the platform will incorporate a chamber pressure superior to the current system in soldiers’ arsenals to ensure that the rounds can still blast through enhanced enemy body armor at up to 600 meters.

The goal, as Norman put it, is to equip infantry soldiers with an automatic rifle “that fires a small bullet at the pressure equivalent to what a tank would fire.”

“The chamber pressure for the standard assault rifle is around 45 KSI [kilopound per square inch], but we’re looking for between 60 and 80 KSI … the chamber pressure when an M1 Abrams tank fires is on that order,” Norman told Task & Purpose. “We’re looking to reach out around 600 meters and have lethal effects even if the target is protected by body armor.”

The NGSW program currently consists of the NGSAR, a Next Generation Squad Carbine (NGSC), and a squad designated marksman rifle, along with specialized ammunition and fire control system. But while the Army had previously focused on fielding an improved carbine with a range and accuracy superior to the standard M4 that would also chamber a round between 6.5mm and 6.8mm, the service recently changed gears to prioritize the muscular automatic NGSAR.

The reason, according to Norman, is the Pentagon’s current shift from the close quarters of urban warfare in Iraq and Syria to the mountains and open terrain of Afghanistan. While the carbine may be well-suited for a knock-down, drag-out brawl while moving house to house in cities like Mosul and Raqqa, it lacks the range to take out Taliban and ISIS fighters in open stretches

“For the past 10 or 15 years, we’ve been really focused on the requirement of lethal effects against unprotected targets,” Norman said. “Now we’re looking at near-peer threats like Russia and others. We need to have lethal effects against protected targets and we need to have requirements for long-range lethality in places like Afghanistan, where you’re fighting from mountaintop to mountaintop over extended ranges.”

The service is certainly working overtime to get the muscular system turning militants into pink mist downrange. Gordon told Task & Purpose that the NGSW systems currently undergoing testing and evaluation by the Soldier Lethality Cross-Functional Team at Fort Benning, Georgia will initially head downrange with the 7.62mm XM11158 Advanced Armor Piercing (ADVAP) round while the service hacks away at a specialized round built to achieve the proper balance between range and lethality.

“The challenge of the 5.56mm is that it doesn’t have enough mass [to defeat enemy body armor],” Norman said, referring to Chief of Staff Gen. Mark A. Milley’s April 2017 testimony before lawmakers on the Army’s growing ammo problem downrange. “But the challenge with 7.62mm ammo is that it has too much mass and not enough propellant. The right solution is somewhere between the two, where you have enough mass to penetrate but you’re still moving fast enough.”....

Lots more at the hyperlink, above. This article is a fluff piece by the NGWS team to knock out the CTSAS weapons and is reasonably accurate, with two glaring errors:

1) The 'next generation squad weapon NGSAR assault rifle' illustrated in the article is actually the Textron/AAI CTSAS polymer CT cartridge LMG. The actual Next Generation Squad Carbine (NGSC) is likely to be an AR derivative and the Next Generation Squad Automatic Rifle (NGSAR) is likely to be an M249 knock off.

2) The chamber pressures for actual tank gun rounds are quite understated. The M829 DU 'silver bullet' war shot APFSDS cartridge actually develops 7,100 bar (104 ksi) in the M1 tank's M256 120mm L44 main gun. Even the older design 125mm L48 Russian 2A46M-x cartridges develop 6,500 bar (95 ksi).

[Viking]

http://www.dtic.mil/get-tr-doc/pdf?AD=ADA434658

On the military side of things;
I got a chance to go back and read that, first thought is that its dated over 13 years old. The military has a tendency to get stuck in doctrine and unable to look past advancements in design and material once they've "assessed" that a particular solution or design is not possible, they will never revisit or review changes in technology unless actively pursuing things way outside of current technological grasp, (electromagnetic / rail guns come to mind)

The problem with the military requesting new or designing new things, not necessarily updating or replacing, is for example when they asked developers to create a replacement for 9mm parabellum, capable of penetrating armor, greater range, better ballistics, and terminal results... two competitors did create a viable solution, NATO decided to adopt one of them, and it was immediately contested by the loosing competitor which caused a deadlock and then neither product was adopted by NATO..

[10x25mm]

ADA 434658, Alternative Case Materials and Design, was written in the same time frame as the initial development of both the True Velocity and CTSAS polymer cases.

[10x25mm]

On the military side of things;
I got a chance to go back and read that, first thought is that its dated over 13 years old. The military has a tendency to get stuck in doctrine and unable to look past advancements in design and material once they've "assessed" that a particular solution or design is not possible, they will never revisit or review changes in technology unless actively pursuing things way outside of current technological grasp, (electromagnetic / rail guns come to mind)

The problem with the military requesting new or designing new things, not necessarily updating or replacing, is for example when they asked developers to create a replacement for 9mm parabellum, capable of penetrating armor, greater range, better ballistics, and terminal results... two competitors did create a viable solution, NATO decided to adopt one of them, and it was immediately contested by the loosing competitor which caused a deadlock and then neither product was adopted by NATO..

BG Anthony Potts, the new commander of Program Executive Office (PEO) Soldier has launched a lightweight 7.62mm ammunition program which probably includes consideration of the True Velocity polymer cases:

http://www.thefirearmblog.com/blog/2...ht-ammunition/

US Army Working on Lightweight 7.62×51 Ammunition
Matthew Moss - 12 June 2018

Representatives from the Army’s Program Executive Office (PEO) Soldier have recently discussed their work to replace conventional brass ammunition casings in an effort to reduce the load on soldiers in the field.

Todd Townsend, Project Manager Maneuver Ammunition Systems with PEO Ammunition, explained that they are “currently working on drop-in replacement ammunition for the existing 7.62 family of weapons optimizing for the M240 family of machine guns. Ounces are pounds. So if we can take a pound out of a Soldier’s weight load, a Soldier could be more effective by carrying other important things.”

The lightweight ammunition program is currently evaluating three concepts for new ammunition casings and comparing their weight and operational characteristic to that of traditional brass ammunition. The first of the three concepts under evaluation is a stainless steel metal injection molded case. The second is a composite brass case with a polymer body and lastly another composite with a stainless steel base and a polymer body. Composite cases are a concept which has been played with since the 1970s.

PEO Ammunition is set to begin the testing phase with these concepts sometime in the next few months. An Army press release confirmed that “Portions of the test data from the new rounds will be sent back to the developers to help improve the product.”

The project is not a solely US endeavor as program managers have confirmed they have partnered with the other services, including the US Special Operations Command, and the British Military.

“We’re looking at other calibers as well. One of them is 50-caliber round,” Townsend said. “We will continue to coordinate within all test areas to make sure that we don’t do redundant or unnecessary testing. The Joint Light Weight Integrated Product Team ensures that all the services are all working toward one common goal of lightening a load.”

Townsend, who previously worked on the 7.62mm Enhanced Performance Round, said that PEO Ammunition is “looking at doing a full-up qualification by the fiscal year 2021. We are aiming for a fielding by FY2022.”

Usually defense contractors front run these announcements with a blizzard of press releases and ads, but there don't appear to be any from True Velocity addressing this evaluation program. True Velocity also holds a number of patents on MIM stainless steel ammunition components, so they could have two candidates under consideration.

Once again, the real impediment here is the raging debate over the armor penetrating power required in the next generation cartridge. Will the Army adopt a standard chamber pressure only lightweight cartridge case a year before the NGWS is fielded? Or will the NGWS program fold up?

[Viking]

I will be interested to see what develops, I understand that the polymer cases have some drawbacks like melting, however the manufacturing process true velocity is using is easily re tooled for new casings and calibers. The question is if it’s possible to get the ultra high velocities with their products in a case that is compatible with whatever idea fairy the military development and research projects take up next.

I think development tends to trend in paths of whomever the current global concern is. From 2000-present concern has largely been focused on the Middle East theatre. Where development in our own armor, armored vehicles and lightening the load of the soldier to carry more rounds/food/water/medical/random. Since just about 2015 or 2016 the focus has been seeing an acceleration in shifting concern to refocus on (not that development ever stopped) being prepared for mega nations with resources to arm and armor their troops, not just guerrilla / ambush combat most recently dealt with. Thus firearms and munitions designed to defeat armor or other cover, defenses and other munitions to defeat drones and missiles and other scary stuff.

Side note, the “idea fairy” is a term our unit used to describe hair brained plans our battalion and brigade level leadership dreamt up in the middle of the night about how to reinvent the wheel and do something “easier, faster, more efficiently, more accurately etc” that really never panned out and we the lowly grunts would have to pay the price for whatever consequences these idea fairies brought up. I can say this now without fear of doing pushups for the rest of my life ... of course I give credit for trying to make things easier but in an environment where feedback doesn’t flow back up for fear of repercussions you just dealt with it and tried to laugh.