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Polymer-cased .50-caliber ammunition is seen at Marine Corps Base Camp Pendleton, California, Nov. 3, 2021. The polymer-cased ammunition is a new technology that reduces the weight of a 100-round linked belt of .50-caliber ammunition by seven pounds, reducing the weight Marines have to transport. (U.S. Marine Corps photo by Cpl. Cameron Hermanet)

Photo by Cpl. Cameron Hermanet

Polymer ammo: A lightweight approach to support the warfighter

13 Jan 2022 | Matt Gonzales, MCSC Office of Public Affairs and Communication Marine Corps Systems Command

The Marine Corps is on a mission: get lighter, more mobile and more lethal.

Marine Corps Systems Command plays a critical role in accomplishing this goal. The command’s Program Manager for Ammunition has been in the process of researching the myriad ways to lighten the warfighter’s load while maintaining or increasing lethality.

One potential solution: polymer-cased ammunition.

In 2020, MCSC awarded a contract to test and evaluate new, lightweight .50-caliber polymer ammunition to lighten the warfighter’s load. The ammunition, to be used in multiple .50 caliber weapon systems, is significantly lighter and easier to haul than the traditional brass cased ammunition.

“This polymer ammunition is an upgrade over the current brass case rounds, as it reduces the overall weight of the cartridges and links,” said CWO3 Chad Cason, the project officer for .50-cal polymer ammunition at MCSC. “That reduction in weight makes a huge difference for Marines.”

On the battlefield, the amount of weight a Marine carries matters. The more weight on their shoulders, the less mobile and mission flexible they could be. MCSC has worked tirelessly to field capabilities that are lighter without compromising lethality.

Polymer is a lightweight, proprietary plastic that weighs less and offers more durability when compared with brass and other metals commonly used in weapon systems. MCSC is working toward replacing brass-cased ammunition with a polymer-cased alternative and traditional metal links with nylon links used to secure ammunition in belts.

“This polymer ammunition also reduces fuel costs not only for aircrafts but also for logistics and supply,” said Cason. “You can fit more ammunition on the pallet, increasing the overall pallet space used on a truck or ship. You can carry more on vehicles into combat or training as well.”

Testing has indicated that polymer rounds are as lethal and as effective as the current brass casing cartridge, said Cason. Upon firing, the polymer ammunition maintains a more consistent velocity when compared with its brass counterpart.

“We are replacing a heavier round with a lighter round that has the same capability, the same lethality,” said Cason. “And when you factor in the weight advantages, using polymer ammunition versus brass is a night-and-day difference.”

Another key advantage of polymer over brass ammunition lies in its structural characteristics. For example, a machine gun typically heats up when Marines rapidly fire brass ammunition. The high temperature can soften the material and affect the bullet’s acceleration.

Polymer cartridges absorb heat expelled from the casing, preventing the machine gun from over-heating. This allows Marines to fire for longer periods. They can also pick up the cartridge case immediately after firing and it will not burn their hand, said Cason.

“Polymer dissipates the heat faster and acts as an insulator at the same time, which is one of my favorite aspects of this ammo,” said Cason. “That is not the case with the brass ammunition.”

In November, Marines with 1st Marine Division tested and assessed polymer ammunition during a limited user evaluation. Cpl. Jarom Hoffmann, a machine gunner with 3rd Battalion, 7th Marine Regiment, emphasized the various advantages lighter-weight ammunition presents to the warfighter.

“This ammo can help us do our job in a way that the rounds are lighter, so we can carry more rounds per Marines,” said Hoffmann. “That is huge for me as a machine gunner.”

Hoffmann also said the ammunition seems to shoot smoother than the brass casings—an aspect of the ammunition that Lance Cpl. Peyton Robinson, a machine gunner with 3rd Battalion, 4th Marine Regiment, also seemed to appreciate.

“In some cases, the ammo cycles through a lot smoother, which allows us to fire more rounds faster,” said Robinson. “Firing more rounds means we have more time on the gun to surprise whatever enemy we’re dealing with.”

Other services are also evaluating additional types of polymer ammunition, including the Army, who is validating a 7.62mm polymer round.

The Army’s efforts on validating the lightweight ammunition is important to the Marine Corps because they are the Single Manager for Conventional Ammunition. The SMCA was established to avoid duplication of efforts in the management of conventional ammunition like 7.62mm.

“If the Army is successful with polymer 7.62mm, fields it and fully integrates it, then it is probable that the Marine Corps will follow suit, especially if polymer cartridges completely replace brass cartridges in certain calibers,” said Cason.

A key goal in MCSC acquiring lighter, more innovative capabilities, such as .50-cal polymer ammunition, is to modernize the Corps. Lt. Col. Brian Wisneski, deputy program manager for MCSC’s PM Ammunition, said such innovation supports Force Design 2030 and the commandant’s vision.

"Polymer ammunition will enhance the Forces’ capability by being more agile in logistical movements and reducing lift requirements in support of stand-in forces deployed in a distributed environment,” said Wisneski. “The ultimate goal would be to adapt this technology across the ammunition portfolio and multiple platforms to save weight while achieving the same desired effects against multiple targets."

Cason said MCSC will continue to hold larger user assessments to test and evaluate the ammunition, soliciting Marine feedback to determine its feasibility in supporting the warfighter. After completion of those exercises, the command will assess data and identify a definitive fielding timeline.

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