Industrial URLLC workloads-coordinated robotics, automated guided vehicles, machine-vision collaboration require sub-5 ms latency and five-nines reliability. In standardized 5G Multicast/Broadcast Services, intra-cell group traffic remains anchored in the core using MB-SMF/MB-UPF, and the Application Function. This incurs a core network path and packet delay that is avoidable when data transmitters and receivers share a cell. We propose a gNB-local multicast breakout that pivots eligible uplink flows to a downlink point-to-multipoint bearer within the gNB, while maintaining authorization, membership, and policy in the 5G core. The design specifies an eligibility policy, configured-grant uplink. 3GPP security and compliance are preserved via unchanged control-plane anchors. A latency budget and simulation indicate that removing the backhaul/UPF/AF segment reduces end-to-end latency from approximate 6.5-11.5 ms (anchored to the core) to 1.5-4.0 ms (local breakout), producing sub-2 ms averages and a stable gap approximate 10 ms between group sizes. The approach offers a practical, standards-aligned path to deterministic intra-cell group dissemination in private 5G. We outline multi-cell and prototype validation as future work.