Gibbz Arms G4 Side Charging Upper Receiver

The Gibbz Arms G4 is the flagship AR-15 small-frame side-charging upper receiver, machined from billet 7075 aluminum and hard anodized. It replaces the standard rear charging handle with a non-reciprocating charge handle that runs along the side of the receiver, which keeps the handle out from under a low-mounted optic and lets a shooter cycle the action without breaking a firing grip or coming off the stock. Gibbz's standard G4 places that handle on the left side as a non-reciprocating charger, and a right-hand configuration is also offered.

It is a stripped receiver, so it arrives as just the side-charging receiver body using Gibbz's Gen2 charging handle, with no barrel, bolt carrier group, handguard, or small parts. Dimensionally it follows standard AR-15 upper architecture, so it accepts a mil-spec barrel nut, common handguards, and a standard BCG. This is the receiver a builder reaches for to assemble a side-charging upper from components rather than buying a complete unit, and it is the receiver Pro2A builds its complete non-reciprocating uppers on.

At $249.95 it sits at the premium end of stripped uppers, which is the going rate for a billet side-charging design versus a sub-$120 forged receiver with a conventional rear charging handle. Budget separately for the barrel, BCG, handguard, and small parts; this receiver is the side-charging foundation, not a complete assembly.