As could be expected (subjectively), the Sig Sauer company was the winner of the procedure for the new US ARMY small arms program known as the NGWS.

The rejected design was the bull pup system by LoneStar Future Weapons/True Velocity which, apart from the above-mentioned trigger system rarely found on the American market, was characterized by a rather unusual look of the silencer.

The contract is scheduled for 10 years and the initial order for new rifles is worth $ 20.4 million. The order naturally includes the XM5 carbine and the XM250 machine gun, new 6.8mm ammunition, spare parts, accessories and manufacturer support.

The above-mentioned models are to replace the M4/M4A1 carbines and the M249 Squad Automatic Weapons, both chambered for the standard NATO 5.56 ammunition, in the line units first. Stopping for a moment at the ammunition, it should be mentioned that the choice of a new shooting platform and ammunition is in fact a considerable revolution, because currently the standard ammunition in NATO is the 5.56x45mm round. The 6.8x51mm ammunition designed by Sig Sauer is an interesting solution in itself, as according to the manufacturer, it provides greater precision and firing range than the 5.56 and 7.62 calibers used so far. The ammunition also has a hybrid design (brass and steel), although it is not as innovative as the competing cartridge that was defeated in the tender, made by True Velocity, which casing is made of polymers.

The pressure of the gases in the chamber when firing a 6.8x51mm round is 80,000 pounds per cubic inch (5155 bar) compared to 60,000 pounds per cubic inch (4136 bar) when firing a 5.56 caliber round. According to experts, it is this difference that provides a greater range of 6.8 mm while maintaining a relatively short barrel length. However, Ian MacCollum of the Forgotten Weapons channel claims that such high pressure in the cartridge chamber can cause faster wear of the weapon. The manufacturer claims that the new weapon requires the barrel to be replaced after about 12,000 shots, and now the standard M4 barrels are replaced after about 6,000.
The new XM5 and XM250, apart from the shooting characteristics mentioned above, also differ in weight from their predecessors. The XM5 (3.76 kg) is heavier than the M4 (approx.3.3 kg) and the XM250 (5.44 kg) is lighter than the M249 (8.2 kg) and the larger M240 (12.7 kg).
The new weapons have be naturally equipped (although it is not known if all of them) with the new XM157 Fire Control Unit hybrid sight by Vortex Optics.

The XM157 sight is an interesting targeting device. It is equipped with an optical sight (originally with a variable 1-8 magnification), a laser rangefinder, a compass, a targeting lasers (IR and classic), a ballistic computer and a set of sensors recording weather conditions. In addition, the XM157 is to be able to connect wirelessly with the still developed Integrated Visual Augmentation System (IVAS) unit to ensure maximum imaging and precision of targeting by each soldier.

It is worth adding that Sig Sauer, after receiving the above-mentioned contract, will become the largest supplier of small arms for the US ARMY. The company is currently supplying the M17 (SIG P320) pistols selected a few years ago as the new US ARMY handgun.

Sources: army.mil, thefirearmblog.com, taskandpurpose.com, americanrifleman.org, armyrecognition.com