Description
HDA3 Stock and Brace for MP5K, SP5K
The HDA3 is a modular, USA-made stock and brace system developed by Haga Defense and A3 Industries. Built for strength, adaptability, and cross-platform compatibility, it delivers premium rigidity, smooth adjustability, and long-term durability without compromising aesthetics.
Features:
- Heavy-duty steel hinge with solid lockup when open or folded. Folds left at a 3.5° cant.
- All-metal internals for durability, including an aluminum cheek-riser button and length-adjustment latch tied into an extruded aluminum spine.
- Offered as a stock with molded extension and textured Santoprene buttpad, or as a brace-ready model designed to accept multiple 1.195″ tube-style arm braces.
- Seven length positions in 0.5″ increments and a three-position cheek riser (0, +0.25″, +0.50″).
Specifications:
- Made in the USA
- 6061 hard-coat anodized aluminum adapter
- Adapter dimensions: 2.85″ H × 1.64″ W
- Includes rubber buffer
- Stock length: 7.93″–10.93″
- Brace mount length: 8.26″–11.26″ (without brace installed)
- Stock weight: 1 lb 5.0 oz
- Brace mount weight: 1 lb 3.5 oz
- Nitride-coated 17-4 stainless steel, left-folding hinge
- Extension: 7-position 6061 aluminum extrusion with 7075 locking latch
- Cheek riser: 3-position polymer riser with anodized aluminum adjustment button
- Polymer components: 30% glass-fiber reinforced nylon
- Textured Santoprene TPE buttpad (stock only)
- Sling mounts: rear sling loop, two steel QD points, one QD point on the adapter
Compatible With:
- MP5K, SP5K
- In-spec clones and custom builds
