Army, Marines getting away from brass case ammo.

[dsculley]

I have a question, not about the case but the bullet selection. Why did the DOD go with the 6.8mm? There are not a lot of bullet choices in 6.8. There are lots more good choices in either 6.5 or 7.0.

 

[243Mendoza]

Brass acts as a heat sink. This removes some of the heat from the action of a machine gun. Polymer doesn't.
Caseless rifle/ammo not new. https://apps.dtic.mil/sti/citations/AD0845570

SIG patent application entitled MULTI-PIECE CARTRIDGE CASING AND METHOD OF MAKING, note that the patent application also describes a multi-piece pistol cartridge case. SIG Cartridge Case Patent Application 2019, US20190226817A1.pdf

The alloys used in the case head and body can be very different then brass that we are used too. The patent is saying pressures as high as 120,000 PSI for rifles.

The hybrid case gets rid of most of the extraction issues of the higher pressure.

Looks expensive!

 

[243Mendoza]

The Green New Deal will kill it since polymer is made of petroleum-based products

The future is here, and the military is getting serious about abandoning brass as the material of choice for ammo casings. Polymer has long been the material under consideration for the future, and it's about to arrive on the battlefield as early as 2023.

All 50 cal, 7.62mm and 6.8mm ammo is being looked at seriously to reduce loads carried by infantrymen on the battlefield. They're talking 30% wt reduction over brass, but in reality aren't we talking about a few grams of wt per cartridge?

Someday I suspect it will trickle down to the commercial market, but not anytime soon so don't go out and hoard all the brass you can find. We'll all be long gone before plastic replaces all casings.

https://www.yahoo.com/news/50-years-army-marine-corps-095548994.html

The Green New Deal Democrats will kill polymer-based cartridges since it is made from petroleum-based products

 

[243winxb]

I cant find much on the polymer case & heat from firing. Mostly from 2005. ? Government secret

Lightweight Cartridge Case.
Much of the weight reduction in the lightweight ammunition developed during this project was derived from the use of materials other than brass for the cartridge case. Elimination of the cartridge case altogether (i.e., caseless ammunition) is the ultimate goal; however, a cartridge case plays an important role in the reliability of the ammunition. Environmental protection is an important function of the cartridge case, particularly the exclusion of moisture. Mechanical protection is also an important function of the cartridge case during shipping, handling, and loading. Cased ammunition has a particular advantage over caseless ammunition when heat management is considered. Much of the heat generated by the burning propellant will be contained within the cartridge case when it is ejected from the weapon, which will reduce the heating rate of the chamber region. In caseless ammunition, the heat will be convected into the chamber, possibly requiring a means of cooling the chamber during sustained firing. Finally, the cartridge case performs the function of sealing the gun chamber and firing pin during a firing. In caseless ammunition, this function must be transferred to the weapon design, potentially complicating the design and increasing the weight of the weapon itself. https://apps.dtic.mil/sti/citations/ADA434627 VERITAY TECHNOLOGY INC

 

[Evan]

I'm curious as to where you found "...a 30% payload reduction transporting ammo around the world..."


Given the polymers are long chain hydrocarbons, I'm not sure the environment wins, in either manufacture, or (lack of) disposal.

Just going off the 30% weight reduction mentioned by the OP. I agree, manufacturing polymers isn't the greenest of industries, but when weighed across the lifespan, does it pay for itself? I'm assuming, probably wrongly, that the military has done some preliminary analysis of how this weight reduction pays off across it's lifespan.

 

[ED3]

Just going off the 30% weight reduction mentioned by the OP. I agree, manufacturing polymers isn't the greenest of industries, but when weighed across the lifespan, does it pay for itself? I'm assuming, probably wrongly, that the military has done some preliminary analysis of how this weight reduction pays off across it's lifespan.

From what I recall from reading this, the 30% weight reduction is the difference from one cartridge to the next,not the amount of weight a soldier is going toe humping. I believe I read it would be a few ounces per soldier.

 

[Evan]

From what I recall from reading this, the 30% weight reduction is the difference from one cartridge to the next,not the amount of weight a soldier is going toe humping. I believe I read it would be a few ounces per soldier.

I was thinking about the portion of it's life on a truck, in an airplane, etc. The solider doesn't carry it all that much, and it costs nothing to have them carry it. Reducing the weight in vehicles, or carrying more ammo and using less vehicles, all adds up across the scale of the entire military.

 

[GotRDid]

Is there any accurate information about the total weight of the polymer cartridge vs a comparable traditional Mil-Spec brass cased round. My little Brother carried 8 - 30 rd magazines on his plate carrier +1 in his M4 during outside-the-wire mounted patrols in Iraq. Even when he was on dismounted patrols, he said he never took less than that. They returned to the FOB much lighter a few times and I'm sure he didn't mind humping the initial weight when things got interesting.
GotRDid.

 

[Texas10]

Brass acts as a heat sink. This removes some of the heat from the action of a machine gun. Polymer doesn't.
Caseless rifle/ammo not new. https://apps.dtic.mil/sti/citations/AD0845570

SIG patent application entitled MULTI-PIECE CARTRIDGE CASING AND METHOD OF MAKING, note that the patent application also describes a multi-piece pistol cartridge case. SIG Cartridge Case Patent Application 2019, US20190226817A1.pdf

The alloys used in the case head and body can be very different then brass that we are used too. The patent is saying pressures as high as 120,000 PSI for rifles.

The hybrid case gets rid of most of the extraction issues of the higher pressure.

Seems intuitive doesn't it, but brass does exactly the opposite, it transfers heat into the chamber. Remember the heat originates inside the case. Polymer is slower to conduct the heat of the combustion into the chamber, the result is less build up of heat in machine gun applications, which is exactly why they're interested in polymer cases. Reference the article I linked.

 

[GerryM]

Caseless that,s a bit different Remington tried it for a while
It looked like a pyrodex tablet with the bullet glued on and a special film on the end lit by an electric charge.

 

[243Mendoza]

Seems intuitive doesn't it, but brass does exactly the opposite, it transfers heat into the chamber. Remember the heat originates inside the case. Polymer is slower to conduct the heat of the combustion into the chamber, the result is less build up of heat in machine gun applications, which is exactly why they're interested in polymer cases. Reference the article I linked.

Agreed. If the heat does not go into the barrel or case, it will go into the gas to increase pressure behind the bullet.

 

[shoobe01]

... The H & K G11 case-less ammo was intriguing, but apparently could not handle the rigors military use.

Everyone informed I have heard says the biggest issue by a very wide margin was the end of the Cold War (not perfect but what is on first issue; better than expected, everyone very excited for it to be issue). A reunified Germany with a (then) declining Russia did not prioritize things like new super high tech small arms. And with the end of the Cold War generally means not many prospects for foreign sales, so it just sorta evaporated.

Germany didn't even buy any useful number of stopgaps like the G.41 (HK33 with STANAG magwell, last round hold open, etc) to equip everyone in the new Army with a NATO common rifle, for: budget reasons. Just did sorta nothing and duct-taped it all together for a decade before they got serious about procurement again.

 

[Texas10]

Is there any accurate information about the total weight of the polymer cartridge vs a comparable traditional Mil-Spec brass cased round. My little Brother carried 8 - 30 rd magazines on his plate carrier +1 in his M4 during outside-the-wire mounted patrols in Iraq. Even when he was on dismounted patrols, he said he never took less than that. They returned to the FOB much lighter a few times and I'm sure he didn't mind humping the initial weight when things got interesting.
GotRDid.

Some selected quotes from the article I linked;

Both Textron and True Velocity maintain that their polymer-cased ammo designs offer about a 30 percent weight savings over brass ammunition, but also bring increased performance.

"Brass is a conductor of heat, and our composite case is an insulator," Hogan said. "Brass conducts the heat during the ballistic event; the brass superheats and then transfers that heat to the chamber of the weapon, whereas polymer insulates the chamber from that heat."

Excessive heat buildup can cause ammo to cook off or explode in the weapon, a problem True Velocity's case technology has licked, he said.

"Anecdotally, we have run cook-off tests through some of the belt-fed platforms and, in order to get the gun even hot enough to be in a position where you could even have a cook off, we have to run brass ammo through a gun to get it hot enough where you can really test our ability to withstand cook-offs," Hogan said.

Good article.

 

[SPQR70AD]

On the issue of wieght, I have a friend who is a sherriffs deputy. The switched to one of the new all copper duty rounds like 60gr I think. He said it made a considerable difference in his duty belt wieght. They only carry 3 mags I think? So for a soldier it may well make a carriabilty difference.

I always knew cops think they are at war with civilians and gear up for it

 

[SPQR70AD]

^^^^^ I ain't reloading for that.

a lot of shooters have enough powder for it

 

[SPQR70AD]

If it saves weight, even a small amount if it's reliable and won't gum up chambers, troops will love it and rightfully so. Humping a combat load is no joke, especially up hill. I've seen guys throw cigarette packs down on the ground trying to lighten the load on a hump, back in the day.

Romans would march 20 miles a day with 40-60 lbs of gear then make camp and dig trenches around the whole camp. some were like towns and the remains are still there. that was just for one night

 

[Gil P.]

This effort (to develop polymer-cased ammo) has been underway for some time... but metal will not be abandoned completely it seems. The new SIG .277 fury round developed for the U.S. Military features a hybrid case, but not polymer with brass lower section. Instead it is mostly brass, but with a harder "alloy" from the head and rim. This allows the case to accept extremely high pressures -- way higher than typical SAAMI maxes for other cartridges.

This is worth reading. I think there may be applications for hunters. Get large magnum velocities with a standard short action receiver shooting a medium-sized cartridge.

Story link (click and then scroll down): https://bulletin.accurateshooter.com/2020/01/shot-show-2020-day-one-opener/

This blows my mind. 3000 fps with a 14 inch barrel and 140 gr bullet Is crazy.

 

[edwardware]

Polymers usually aren't very energy efficient to recycle. Brass is very recyclable. It would be interesting to see if this ammo would be an actual "carbon footprint" reduction or not when considering the full lifespan.

You ask an interesting question. I can tell you that Product Lifecycle Analysis, in nearly every case, is rife with fraud and deceit, or at least incompetence. Like statistics, you can make it say anything you want, (ie battery powered cars are beneficial for the environment, etc).

Hopefully the DoD doesn't care that much about carbon footprint.

 

[tsyarnall]

Out of pure curiosity, I discovered the case of the round used in the M1 Abrams is consumed during firing. All that is left is the base and its reusable.

Yes, it is a cellulose case (made of a paper product).

 

[243Mendoza]

You ask an interesting question. I can tell you that Product Lifecycle Analysis, in nearly every case, is rife with fraud and deceit, or at least incompetence. Like statistics, you can make it say anything you want, (ie battery powered cars are beneficial for the environment, etc).

Hopefully the DoD doesn't care that much about carbon footprint.

Like leadless bullets?