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GUNBUILDER'S LOWER PARTS KIT FOR AR-15 LOWER Reviews & Ratings

CMMG® Lower Parts Gunbuilder's Kits contain the needed parts to complete an AR-15 lower receiver. These kits come less the trigger, grip and trigger guard.

INCLUDES:

Takedown pin
Receiver pivot pin
Takedown pin detent (2)
Takedown pin detent spring (2)
Hammer and trigger pin (2)
Safety selector
Selector detent
Magazine catch
Magazine catch spring
Magazine release button
bolt catch
Bolt catch plunger
Bolt catch spring
Bolt catch spring pin
Buffer retainer
Buffer retainer spring

See all of our AR15s and AR15 parts here.

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2 Stars

Reviews Summary

Customers consistently appreciate the GUNBUILDER'S LOWER PARTS KIT for its quality, ease of installation, and organized packaging. Many highlight its value without unnecessary components. However, some have reported issues with specific parts like the safety selector and fitment on certain lowers. Overall, it's a reliable choice for those customizing their AR builds.

What Reviewers Are Saying

Product Quality

82%

The quality of the parts is consistently praised across reviews. Many users find the machining and finish excellent, noting that the parts function smoothly and fit well in various lower receivers. However, a few reports indicated problems with specific parts, such as the safety selector not meeting expectations.

Organization and Packaging

75%

Reviewers commend the organized packaging of the kit, which includes labeled compartments, making assembly much easier. This thoughtful packaging helps prevent mix-ups and assists beginners, enhancing the overall building experience.

Customization Flexibility

68%

Many users appreciate that the kit omits components they may not need, such as grips and triggers, allowing for a more personalized build. This flexibility is a significant advantage for experienced builders looking to select their preferred parts.

Ease of Installation

71%

The installation of parts is generally described as straightforward, with reviews noting that the fit is tight yet manageable. Users have shared positive experiences with assembly, aided by the clear part labeling and organized layout.

Value for Money

70%

A significant number of reviews highlight the kit as a cost-effective option, providing high-quality parts at a reasonable price. Many customers have compared it favorably against other kits, feeling it delivers robust performance without extraneous costs.

Occasional Quality Control Issues

16%

Though many reviews are positive, a few customers reported specific quality control issues, particularly with individual parts like the safety selector or inconsistent fitment. This indicates that while the overall product quality is high, there may be occasional variations.

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AR-15 parts

Worked as advertised.

by William McShane on March 30, 2026

Verified Purchase

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Worked great

All parts there. All parts fit. All parts function. Worked great.