Specialized Tactical Systems is excited to introduce the STS416 A1 Lower. Over the past six months, we meticulously laser-scanned, measured, and analyzed original HK MR556, BRN-4, and MR223 lower receivers to craft these replicas. Every detail, from dimensions and aesthetics to engravings and hues, makes this receiver almost identical to HK specifications and standards. While HK 416 forgings are no longer available, our lower receiver is precision-machined from billet 7075 T6511. We have used laser scanners and CMMs to ensure that external aesthetics, especially those aligning with the upper receiver, resemble the original HK 416 forged lower receivers.

Established in 2008 in Ogden, Utah, Specialized Tactical Systems specializes in designing and manufacturing lower receivers, firearms, suppressors, and other components. As a comprehensive Aerospace and Firearm CNC shop with 3-5axis capabilities, STS oversees all engineering, design, testing, and production of its offerings. While we primarily serve as an OEM for renowned firearm brands, the STS416 A1 Lower is a unique STS project available directly to consumers. To ensure legal compliance and offer customization options, the “HK” engraving is omitted from the lower.

Can only Ship from our STS FFL to another FFL, please have your FFL or you email a PDF copy of their FFL with your name and order # in the subject line to: sales@specializedtactical.com

Lead time is currently 2-3 weeks.

Standard Serial#s begin with the 88- prefix, Custom can be what you like up to 11 digits

Material: 7075 T6511 AL
Coating: Type III with Teflon