Receiver

Receiver is the central structural component of a firearm that forms the constructional foundation of the entire rifle. On the AR15 platform, the receiver is divided into two separate parts: the Upper Receiver and the Lower Receiver. This split is one of the key design features of the AR system and allows for easy modularity, servicing, and weapon customization. The receiver is therefore the fundamental building block of AR15 rifles. Dividing it into upper and lower receivers enables unique modularity, simple upgrades, and extensive customization options. This design is one of the main reasons behind the massive popularity of AR15 platforms in the military, among civilian shooters, and in airsoft.

Complete Noveske AR15 receiver

Upper Receiver

The upper receiver contains key functional components of the weapon related to firing and cycling:

the barrel and its mounting,
the bolt and bolt carrier (bolt / bolt carrier group),
the gas system (on real firearms and GBBR systems),
the top mounting rail (RIS) for optics.

On AR15 rifles, the upper receiver is typically made from aircraft-grade aluminum (e.g. 7075-T6); in airsoft it is also commonly aluminum or alloy. It bears the main mechanical stress and has a crucial impact on accuracy and reliability.

Lower Receiver

The lower receiver is considered the “heart” of the weapon, as on real firearms it represents the legally registered component. It contains:

the trigger mechanism (trigger group),
the bolt catch (bolt catch),
the magazine release (magazine release),
the pistol grip and buffer tube with stock.

In airsoft guns, the lower receiver determines gearbox compatibility (AEG) or compatibility with the trigger mechanism (GBBR). In gas-powered AR15 systems (e.g. MWS, CGS), the lower receiver is the area where durability and manufacturing precision are most critical.

Why the AR15 receiver split is so important

Modularity: the ability to combine different upper and lower assemblies.
Easy upgrades: replacement of the barrel, bolt, trigger, or stock.
Service and maintenance: simple disassembly without tools.
Role customization: CQB, DMR, duty, or sport configurations.

Receiver in airsoft

In airsoft, the receiver fulfills the same structural role as in real firearms, but it also:

affects V2 gearbox compatibility in AEG rifles,
determines fitment quality and longevity in GBBR systems,
influences ergonomics and the realistic appearance of the replica.

A high-quality CNC-machined aluminum receiver offers better strength, tighter tolerances, and a more realistic feel than cheaper alloy or plastic alternatives.