Phase 5 RMSA Rifle Mini Stock Assembly — Black Aluminum

The Phase 5 RMSA (Rifle Length Mini Stock Assembly) is a combo kit that pairs Phase 5’s Universal Mini Stock (UMS) with a rifle-length HexOne buffer tube to deliver a compact fixed-stock solution for AR-platform rifles. The HexOne buffer tube is cut from 7075-T7 and the UMS is machined from 6061-T6, both produced from U.S.-sourced raw billet aluminum. The UMS was designed with a smaller footprint and reduced bottom curve to provide a more secure chest anchor and easier transitions in and out of position. The UMS is also compatible with a number of other buffer tubes, including Mil-spec carbine receiver extensions and most round tubes.

Key Specifications

• The kit includes the Universal Mini Stock (UMS) as the fixed stock solution.
• The assembly ships with a HexOne rifle-length buffer tube included.
• The HexOne buffer tube is manufactured from 7075-T7 aluminum.
• The Universal Mini Stock (UMS) is machined from 6061-T6 aluminum.
• Finish on the assembly is Black.
• The product is listed as a Stock Kit.
• Compatible firearm models are listed as AR15/AR10.
• The UMS is compatible with Mil-spec carbine receiver extensions and most round tubes.
• All major components are precision machined from U.S.-sourced raw billet aluminum.
• The HexOne tube features a hexagonal, thicker design intended to be more rugged than a standard mil-spec receiver extension.

Purpose-built for shooters seeking a compact, durable fixed-stock option for AR-pattern rifles, the RMSA combines robust materials and precision machining to deliver a low-profile anchor and reliable performance in the field. Its compatibility with common buffer tubes and the inclusion of Phase 5’s HexOne tube make it a practical choice for builders and operators who want a sturdy, space-efficient stock assembly without excess bulk.