RUGER 28500 AR LOWER STRIPPED LOWER RECEIVER MULTI CALIBER BLACK

The Ruger AR Lower Stripped Receiver (28500) is a multi-caliber AR-platform lower receiver machined from 7075-T6 forged aluminum, built for custom AR builders, gunsmiths, and experienced shooters who want a mil-spec foundation from a domestic manufacturer at a competitive price point. This stripped AR-15 lower receiver for custom rifle builds and multi-caliber AR configurations ships ready for a standard mil-spec lower parts kit and any compatible AR upper receiver, giving the builder a high-quality aluminum forging as the starting point for a purpose-built rifle.

Key Features

• Part number: 28500
• Caliber compatibility: Multi-caliber
• Material: 7075-T6 forged aluminum
• Finish: Black hardcoat anodized
• Tolerances: Mil-spec throughout
• Magwell: Broached to mil-spec dimensions
• Fire control pocket: Full-cut inlet
• Tension screw: Adjustable upper-to-lower fit screw included
• Action: Semi-automatic
• Configuration: Stripped, no fire control components included
• Compatible with: Standard mil-spec AR lower parts kits and AR-platform upper receivers

Special Features

• The 7075-T6 aluminum forging uses the same alloy specification required by the U.S. military for M16 and M4 lower receivers, providing the tensile strength and dimensional stability needed to handle the cyclic stress of sustained semi-automatic fire across a wide range of AR-platform calibers
• Broaching the magwell to mil-spec dimensions ensures consistent magazine fit and positive lockup with any standard STANAG-pattern magazine, eliminating the loose or binding magazine seating that can occur with receivers cut to looser tolerances
• The full-cut fire control pocket is machined to accept any standard mil-spec trigger group including drop-in cassette systems, single-stage and two-stage triggers, andoldie-style mil-spec components without fitting or modification
• The included adjustable tension screw threads into the buffer tube tower and contacts the rear of the upper receiver, allowing the builder to dial out any play between the upper and lower without shimming or fitting, producing a tight, rattle-free assembled rifle
• The hardcoat anodized finish penetrates the aluminum surface rather than sitting on top of it, producing a surface hardness that resists scratching, abrasion, and corrosion through years of range use and field carry without the thickness variation that paint or coating adds to dimensional surfaces
• Ruger machines this lower using the same CNC equipment and quality controls applied to their complete AR-platform rifles, giving the buyer a receiver built to the same standard as a production firearm rather than a commodity part sourced from offshore supply chains

Practical Benefits

• The multi-caliber designation means this lower pairs with upper receivers in 5.56 NATO, 300 Blackout, 22 LR conversion kits, and any other AR-compatible caliber that uses a standard lower interface, giving the builder one registered lower that supports multiple upper configurations
• The mil-spec fire control pocket and magwell accept parts from any reputable manufacturer in the AR accessories market, keeping the builder free to select trigger groups, grip assemblies, and lower parts kits from the full range of available components without compatibility concerns
• The adjustable tension screw saves the builder the time and cost of fitting aftermarket hardware to eliminate upper-to-lower play, a step that many budget receivers require before the assembled rifle feels finished
• The 7075-T6 forging provides the structural margin needed for suppressed use, pistol-caliber carbine builds, and other applications that place higher cyclic loads on the lower receiver than standard 5.56 carbine configurations
• Whether you are building a dedicated precision upper on a quality lower, assembling a multi-upper system around a single registered receiver, or starting a custom AR project that calls for a domestically made forging you can trust, your Ruger AR Lower gives you a mil-spec foundation built to the same standard as a complete production rifle

The Ruger AR Lower Stripped Receiver (28500) is a solid fit for the AR builder who wants a mil-spec 7075-T6 forged aluminum lower from a domestic manufacturer, built to accept any standard parts kit and any compatible upper receiver across multiple caliber configurations.