Geissele 05314 Reaction Block — Black Steel for AR-15/M4/M16

Description

The Geissele Reaction Block 05314 is an armorer’s tool designed to aid in lower-receiver assembly and maintenance for AR-15/M4/M16 platforms. After installing a mil‑spec buffer tube, the lower receiver slides into the Reaction Block at the 12, 3, 6 and 9 o’clock positions to provide a stable working orientation. The block lets the armorer reposition the receiver between indexed positions while keeping both hands free to work, simplifying tasks such as installing the buffer retainer nut and performing other lower-receiver operations. Constructed for shop and bench use, it is built to support repeatable, accurate assembly and maintenance workflows.

Key Specifications

• Product type: Reaction Block for lower-receiver work.
• Manufacturer: Geissele Automatics.
• Model/part number: 05314.
• Compatibility: AR-15/M4/M16 lower receivers.
• Buffer tube requirement: Mil‑Spec buffer tube only.
• Indexed positions: accepts the lower at 12, 3, 6 and 9 o’clock for repeatable work.
• Construction/finish: Black steel, per product naming and attributes.
• Primary function: provides an ultra-stable platform for performing lower-receiver operations and installation of the buffer retainer nut.

Purpose-built for armorers and professional builders, the Geissele Reaction Block streamlines lower-receiver assembly and routine maintenance by providing a secure, indexed platform that frees both hands for precise work. Its straightforward design and durable construction make it a practical addition to any bench where AR-15/M4/M16 lowers are built or serviced, helping reduce setup time and improve consistency across builds.