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.