AD-509T | Holosun 509T Lower 1/3 QD Mount

The AD-509T is a compact, quick-release lower 1/3 mount purpose-built for the Holosun 509T footprint. It is a one-piece design precision machined from aircraft-grade aluminum and finished in a durable Mil-Spec hard coat anodize. The mount employs American Defense’s patented QD Auto Lock Lever system to provide secure retention across a range of rail tolerances. Typical applications include use on AR pistols and other compact rifle platforms where a lightweight, low-profile mounting solution is required.

Product Specifications

• The manufacturer is American Defense Mfg.
• The model is AD-509T.
• The mount fits the Holosun 509T Footprint.
• The size is specified as Lower 1/3.
• The product type is Mount.
• The subcategory is Optic Specific Mounts.
• The finish is hard coat T3 Mil-Spec anodize.
• The color is Black.
• The primary material is 6061 T6 aluminum.
• The unit is a one-piece, precision machined construction.
• The mounting system uses a Patented QD Auto Lock Lever quick-release mechanism.
• The product is described as Quick Release for fast installation and removal.
• Designed for Holosun 509T red dot use on AR pistols and compact platforms.
• The listing UPC is 810008517642.

Compact, robust, and engineered for dropped-on optics like the Holosun 509T, the AD-509T lower 1/3 QD mount delivers a low-profile mounting option without excess weight. Its one-piece 6061 T6 construction and Mil-Spec finish provide corrosion resistance and repeatable alignment, while the patented QD Auto Lock Lever accommodates rail variances for reliable engagement. For shooters seeking a dedicated lower-third mounting solution for competition-oriented or carry-weight-sensitive builds, this mount offers a precise, no-nonsense option.