The U.S. Army is gearing up to select a new rifle to be carried by most front-line units into battle, moving on from its mainstay M4 carbine after more than 25 years of service. The Next Generation Squad Weapons (NGSW) contract would be a nice payday for the defense company named the eventual winner, with a total value estimated to be more than $1.5 billion.

In late August, the Pentagon narrowed the competition down to three vendors, with privately held Sig Sauer and divisions of Textron (NYSE:TXT) and General Dynamics (NYSE:GD) making the final cut, but little was known about the offerings at that time.

In the weeks since, all the companies have unveiled details about the guns they hope will succeed the M4 and related M249, which have been in service since replacing the Vietnam War-era M16 in 1994. The Pentagon wants the new rifle to engage targets 600 meters away, about double the lethal range of the M4, and to be able to use advanced targeting systems and defeat existing body armor.

Here's a look at the guns the three finalists are bringing to the fight.

The firearms specialist

Sig Sauer, which won a contract in 2017 to replace the Army's mainstay M9 handgun with a new high-tech system, is touting a design that is lighter than the current generation of weapons, with better ergonomics and less recoil. The core of the submission is newly developed ammunition that should provide increased velocity, distance, and accuracy, while being easier for soldiers to carry.

The weapons Sig Sauer entered into the Army competition

Sig Sauer's NGSW entry. Image source: Sig Sauer.

"Using patent-pending technology the SIG SAUER Ammunition division has engineered a completely new cartridge resulting in a more compact round, with increased velocity and accuracy, while delivering a substantial reduction in the weight of the ammunition," CEO Ron Cohen said in a statement last month announcing the company's participation in the competition.

Sig Sauer also notes its entry provides "single-source manufacturing" of the weapons, ammunition, and accessories, which it says allows for increased capabilities and less risk to the U.S. Army, compared to its competitors' approach of partnering with a number of companies and submitting a bid as a team.

A maturing design

Textron's bid is focused on the company's well-regarded cased-telescoped (CT) design, in which the projectile is seated within a cylindrical case. The company claims that design allows for substantial weight savings, which in turn drives improved maneuverability and accuracy.

The company developed its CT design in part for the Army's since-canceled Lightweight Small Arms Technologies machine-gun program. Textron's NGSW entry appears to borrow from that design, and update it to handle the requirements of the current competition.

Textron's entry on display at a vendor booth

Textron's NGSW entry on display. Image source: U.S. Army photo by Markeith Horace, Maneuver Center of Excellence, Fort Benning Public Affairs Office.

Textron has enlisted some allies to help it make its bid. The company is working with German contractor Heckler & Koch for design, research and development, and manufacturing capabilities, and with a unit of Olin for small-caliber ammunition production.

"We have assembled a team that understands and can deliver on the rigorous requirements for this U.S. Army program with mature and capable technology, reliable program execution and dedicated user support," Textron Systems vice president Wayne Prender said in a statement.

The deal would be a nice win for Textron, an industrial conglomerate that is increasingly turning to defense as a source of future growth.

The "bullpup" makes its stand

General Dynamics has been the most tight-lipped about its submission, but it provided an unveiling of sorts this week at the Association of the United States Army's annual meeting. At the event, the company provided a promotional video showing its prototype in action.

The General Dynamics submission is notable in that it's the only one to replace the traditional M16 layout that the Army has used since the 1960s with a so-called "bullpup" design, moving the magazine to behind the trigger on the rifle. In theory that allows for a longer barrel on a compact frame, which should improve the range of the rifle.

The configuration is used internationally and has been pitched to the U.S. Army before, but so far without much luck. General Dynamics and manufacturing partner Beretta USA seem to be betting that the government will be open to the concept this time around, if they can prove the design offers better performance.

Expect a tough fight

The Army has requested that each of the three vendors submit 53 rifles, 43 automatics, and 850,000 rounds of ammunition for testing, which is expected to take about two and a half years. The goal is to have a finalist selected and fielding to begin by the end of 2022.

Not all personnel will get the new weapon, but the Army is expected to eventually field upwards of 250,000 systems to front-line units. The total award value for the winner is likely to be significantly higher over time when ongoing ammunition sales are factored in.

It's hard to break down the competition based on prototypes that haven't yet competed on the field, but Textron's mature, familiar design is likely to be welcomed by the Army. And Sig Sauer's handgun win could work against it in this competition, given the Pentagon's stated goal of funding a healthy and diverse supplier base and fears of becoming too reliant on a small number of suppliers. 

General Dynamics appears to be the wild card in the competition. The bullpup might be the superior design, but it seems likely it would have to vastly outperform its rivals for the Army to disrupt the status quo.

Pencils are down, and the designs are complete. It's now time for these weapons to show their mettle in the field.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.