Enhanced HK 416A3-Style Lower with Ambi Controls

The STS416 A3 Lower features the classic HK 416 design—enhanced with A5-style ambidextrous controls for improved functionality. Built from the ground up using laser scanning and CMM analysis of the MR556, MR223, and BRN-4 lowers, this billet receiver delivers an incredibly accurate and aesthetically correct replica. (This lower was not produced by HK and is a hybrid of the old and new)

Why Billet? Why It Takes Time

With HK 416 forgings no longer available, this lower is CNC-machined from 7075 T6511 billet aluminum. Matching the contours, fit, and finish of forged HK lowers using billet requires a complex, time-intensive machining and deburring process—executed to exacting standards.

Specs & Options

• Material: Billet 7075 T6511 Aluminum

• Finish Options:
  • Type III Hardcoat Anodized with Teflon
  • Proprietary Cerakote RAL8000 Blend

• Controls: A5-Style Ambidextrous Bolt Release & Mag Release

• Serial Numbers:
  • Standard format: 88-XXXXXX
  • Custom serials available (to match your HK upper serial, etc.)

⚠️ HK markings are not included for compliance. For engraving, we recommend BlackOps Defense. (we can ship directly from us to them, contact BlackOps defense and provide STS with your BlackOps Defense order number to let them know what to do with your lower)

Shipping & FFL Instructions

This product must ship from our FFL to your FFL.
Please have your FFL dealer email a signed PDF copy of their license to:

📧 sales@specializedtactical.com
Subject Line: Your Name + Order #

Looking for a Matching Upper?

We recommend pairing this lower with the HK416A5 upper from HKParts:

🔗 HKParts.net – HK416A5 Upper (RAL8000)

If you are new the HK world and would like help understanding the various models, please visit our friends at: HKPro.net