CMMG AR-15 Lower Parts Kit

Description

CMMG AR-15 Lower Parts Kit

The CMMG Lower Parts Kit hands the AR-15 builder every internal component a stripped lower needs, because a build only stalls when a single spring or detent goes missing. In particular, this kit suits the shooter tackling an AR-15 lower build from a bare receiver, whether that is a first project or the tenth rifle off the bench. Since the kit includes the full fire control group, safety selector hardware, magazine catch assembly, pivot and takedown pin sets, and an A2-style pistol grip, there is no need to source parts piecemeal from a dozen vendors. CMMG packages every part into color-coded bags organized by assembly stage, so the parts that go in together stay together on the bench.

Additionally, CMMG builds the kit to mil-spec dimensional standards, so it drops into any mil-spec AR-15/M16 lower receiver without modification. Because of that fit, the build moves from parts bag to function test without any hand-fitting. For that reason, pair it with a buttstock or pistol brace kit to finish the lower group and move straight to testing.

Key Features — CMMG Lower Parts Kit

• Complete fire control group, including trigger, trigger spring, hammer, hammer spring, disconnector, and disconnector spring
• Bolt catch assembly ships with roll pin, plunger, and spring included
• Trigger guard assembly ships with its roll pin
• Safety selector kit includes detent and spring
• Magazine catch, catch spring, and release button complete the mag-well hardware
• Pivot pin and takedown pin sets ship with matched detents and springs
• A2-style molded-polymer pistol grip includes mounting screw and washer
• Buffer retainer and buffer retainer spring finish out the receiver extension mount
• Color-coded packets group parts by assembly stage for straightforward installation

 

Why This Product Stands Out

CMMG has built AR-15 lower parts for years, and that experience shows in the fit between components most builders never think about. Specifically, the trigger and hammer pins seat cleanly, the bolt catch plunger does not bind, and the safety selector clicks with the same crisp detent feel of a much pricier trigger group. Because every part in this kit meets mil-spec dimensional standards, it drops straight into a properly machined AR-15 lower without the fitting and filing that plagues cheaper knockoff kits.

The color-coded bagging system deserves real credit. Rather than dumping forty loose parts into one bag and leaving the builder to sort pins from detents, CMMG groups components by the order they go in — fire control group, safety hardware, magazine catch assembly, buffer retainer — so the build follows a logical sequence from empty receiver to functioning lower. That organization matters most on a first build, since misidentifying a bolt catch spring for a buffer retainer spring can cost an afternoon. Notably, that same sequence makes the kit easy to inventory on a repair bench, since spare parts stay grouped by function instead of loose in a bin.

For the builder stocking a parts bin for repairs or running a build line, this kit’s consistency is the real value. Every unit ships with the same trigger, the same pin tolerances, and the same grip, so there are no surprises between kit number one and kit number twenty. As a result, a shop can standardize on one kit across every build without tracking part-to-part variance.

Ideal Use Cases

• Completing a stripped AR-15 lower receiver for a first build
• Rebuilding or repairing a worn lower parts group
• Stocking spare fire control components for a build line or gunsmith bench
• Pairing with a buttstock or pistol brace kit to finish a custom lower

 

Technical Specifications

 

 

Compatibility Information

Lower Receiver Compatibility: Fits mil-spec AR-15/M16 stripped lower receivers.

Pairs With: A buttstock or pistol brace kit completes the lower receiver group; this kit does not include a receiver extension, buffer, buffer spring, or stock/brace assembly.

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Manufacturer: CMMG | Model: Lower Parts Kit, AR15 | Type: Lower Parts Kit | UPC: 852005002080 | SKU: 55CA6C5