General Dynamics has finally unveiled their entry into the U.S. Army’s Next Generation Squad Weapon competition, officially confirming the longstanding rumors that their rifle would utilize a bullpup design. Unlike the Army’s existing M4 service rifle, which carries the magazine and chambers the round forward of the operator’s hand, a bullpup rifle handles those functions behind the operator’s hand, offering distinct advantages and disadvantages when compared to a more traditional rifle design.

The RM277 takes its name from the inch-equivalent of the new standard ammunition size the Army is looking to adopt: 6.8mm, which translates to .277 inches. General Dynamics’ service rifle and squad automatic weapon share an architecture, apparently utilizing the same basic feed design and layout. The squad automatic weapon variant, however, seems to carry a longer barrel. Both versions are shown in marketing pictures utilizing a Delta P designed suppressor. The suppressors utilize 3d printing in the production of their cans and are supposed to last the life of the weapon’s barrel, according to General Dynamics.

General Dynamics explained that the RM277 utilizes a “gas and recoil operated, impulse averaged, air cooled” system, with both iterations of the platform feeding through magazines. This may be a setback for the squad automatic weapon variant, as its competition from both Textron and SIG Sauer are belt fed.

The weapon’s ergonomics borrow heavily from the M4, including its pistol grips and the location of its ambidextrous safety selector. These design cues were intentionally carried over to ease the transition for soldiers that learned to shoot using the older rifle. One significant departure in the operation selection on the weapon, however, is the switch to transition from semi-automatic to automatic fire, which on the RM277 is accomplished by sliding a selector above the safety over laterally.

These rifles are chambered in 6.8mm polymer-cased rounds that were developed by True Velocity for the platform. The Army is expected to adopt a polymer-cased round as its new standard for a number of reasons, including the reduction in overall weight, cost effectiveness, and a reduced degree of heat conductivity. The weight savings is of particular import to today’s soldiers; some of whom are carrying well over a hundred pounds of gear into the fight.

“True Velocity’s 6.8mm composite case design produces a level of performance, consistency and efficiency never before seen in small arms ammunition,” said Chris Tedford, president and chief operating officer for True Velocity.

The RM277’s bullpup design is a significant departure from the traditional designs offered by the competition at Textron and SIG. Bullpup designs do allow for a shorter overall weapon while retaining a longer barrel for muzzle velocity and accuracy. However, this rifle design is also historically more complex, requiring longer trigger and other control linkages. This can cause issues with malfunctions and reliability, as well as issues with repairing the weapon in-field. It’s not clear what steps General Dynamics may have taken to offset these disadvantages in their design.