The 360 Precision 15″ Builder Set is a matched three-piece kit that gives you the foundation of a custom AR-15 build: a billet 7075-T6 upper receiver, a billet 7075-T6 HD15 Gen2 ambidextrous lower receiver, and a 15-inch 6061-T6 extruded aluminum M-LOK handguard. All three components are machined in-house and finished together so the color, texture, and fit are perfectly matched.

A builder set is the starting point for a ground-up custom build. You add your own barrel, trigger, BCG, charging handle, buffer assembly, stock or brace, and small parts. If you want 360 Precision to assemble everything for you, that is what the complete rifles (Recon, BR1, Evolution, Bandit) are for. The builder set is for shooters who want to pick every component themselves while starting from a premium, American-made billet foundation.

Who should buy this builder set?

• Experienced builders who want full control over barrel, trigger, BCG, and stock selection while starting from a premium billet platform.
• First-time builders who want to learn the AR-15 platform by assembling it from components, with a matched receiver set that eliminates compatibility guesswork.
• Shooters on a budget who want billet 360 Precision quality now and plan to add their barrel, trigger, and internals over time as budget allows.

Why buy a matched builder set instead of separate receivers?

Three reasons:

• Matched fit: The upper and lower are machined and QC’d together. The integrated tension screw on the HD15 Gen2 lower eliminates the wobble and play that is common when mixing receivers from different manufacturers.
• Matched finish: All three pieces are coated in the same batch, so the color and texture are identical. When you buy receivers and a handguard from three different companies, finish mismatches are almost guaranteed.
• Matched geometry: The handguard is designed specifically for the 360 Precision upper receiver’s barrel nut. It installs cleanly, aligns perfectly, and creates a unified look from the receiver face to the muzzle.

Other finish options

This is the anodized version. The same builder set is available in Single-Color Cerakote, ETC Camo, Custom Camo, and Battleworn Cerakote. All finishes use the same billet receivers and handguard. A 13.5-inch handguard version is also available for shorter barrel builds.

If you only need the upper and lower without the handguard, our receiver sets are available at a lower price.

Frequently Asked Questions

What is included in the builder set?

Three items: (1) HD15 billet upper receiver with dust cover, (2) HD15 Gen2 billet ambidextrous lower receiver (stripped, no trigger or internals installed), and (3) 15-inch M-LOK handguard with Picatinny top rail. Everything else (barrel, BCG, charging handle, trigger, grip, buffer assembly, stock, muzzle device, gas block, gas tube, lower parts kit) is purchased separately.

Do I need an FFL to buy a builder set?

Yes. The builder set includes a lower receiver, which is the serialized, regulated component of an AR-15. It must ship to a licensed Federal Firearms Licensee (FFL) for a background check and transfer, just like buying a complete rifle.

Will this lower work with any AR-15 upper?

Yes. The HD15 Gen2 lower is machined to Mil-Spec dimensions and accepts any standard AR-15 / M4 upper receiver. It will work with the included 360 Precision upper and with uppers from Aero Precision, BCM, Daniel Defense, or any other Mil-Spec manufacturer. The tightest fit will be with the matched 360 Precision upper because they are machined and QC’d as a pair.

What is the difference between the anodized and Cerakote builder sets?

The components are identical. The only difference is the finish. This anodized version uses Black Type III Mil-Spec hard-coat anodize, which is durable, proven, and the most affordable option. The Cerakote versions give you color choices (single color, Battleworn, ETC camo) at a higher price point.

How does this compare to an Aero Precision or Radian builder set?

Aero Precision M4E1 builder sets ($300 to $400) use forged receivers, which are strong and functional but do not offer the same tight tolerances or aesthetic refinement as billet. Radian AX556 builder sets ($1,100+) are billet with fully ambidextrous controls and premium machining. The 360 Precision builder set ($660 to $680) sits between them: billet 7075-T6 construction with ambidextrous controls at roughly half the cost of a Radian set.