Rossi M4 Neptune DEVGRU-BK 9 inch (ETU Programmable Trigger - Black)

Overview & Key Features

According to the listing by MaxAirsoft, this model is a full-metal M4-style (DEVGRU/416) replica featuring:

• A Gen2 gearbox equipped with a Quick Spring Change (QSC) system and a rotary hop-up chamber for rapid adjustments and maintenance.

• A programmable electronic trigger (ETU) system and MOSFET for improved trigger response and firing control.

• A 6.02 mm precision inner barrel and a high-speed motor to a solid balance of accuracy and rate of fire.

• A retractable telescopic stock with internal battery space, a free-float handguard, and folding front and rear sights.

• Comes with 2 × 120-round mid-cap magazines, but battery and charger are not included.

• Offered with a 1-year warranty from the seller.

And more precisely, the technical specs are:

• Power: Approximately 0.9 J (around 300 fps with 0.20 g BBs)

• Effective Range: Up to ~50 m

• Length: Adjustable between ~740-810 mm

• Weight: Approximately 3.08 kg (3080 g)

• Battery Type: Compatible with 7.4 V or 11.1 V LiPo batteries

• Fire Modes: Safe, semi-auto, and full auto.

Notable Design & Build Elements

A feature spotlight from 0'20 Magazine highlights:

• A CNC-machined, anodised 9″ Daniel Defense-style handguard with full RIS on all four sides, giving both strong aesthetics and practicality for accessories.

• A muzzle styled after the SureFire SOCOM RC4 prong design, with QD compatibility for attaching silencers like KAC-style suppressors.

• CNC internal upgrades, such as 8 mm bearings, an all-metal piston with metal teeth, and a reinforced POM piston head with a bearing - boosting durability and smoothing operation.

• Inclusion of a spring guide with bearing for quick spring adjustments, an aluminium nozzle with gasket, and a high-precision trigger setup delivering average around 330 fps output with the 6.02 × 270 mm barrel.

The Rossi M4 Neptune DEVGRU-BK 9" seems to offer a strong combination of robust construction, internal upgrades, and out-of-box functionality, all at a competitive price point. The programmable trigger and MOSFET, plus the handy quick spring change system, make it appealing for players wanting both performance and customization.