The American Defense AD-509T QD Mount is a quick-detach rifle mount purpose-built for optics using the Holosun 509T footprint — this version at low height, the most compact option, ideal for shotguns, PCCs and setups without iron sights. ADM's patented Auto Lock QD lever attaches and removes the optic fast while holding a secure, repeatable return-to-zero on Picatinny rails.
Machined from 6061-T6 aluminium with a Type III hardcoat anodised finish. Made in the USA.
Height: Low Mount — also available in Absolute Co-Witness and Lower 1/3 Co-Witness.
How It Compares
Running an AEMS optic instead? See the AD-AEMS mount. Browse all red dot mounts and enclosed red dots; read our co-witness heights guide.
Ideal For
- Holosun 509T optics on shotguns, PCCs and carbines
- Compact low-profile setups
- Quick-detach with return-to-zero
Key Features
- Purpose-built for Holosun 509T footprint
- Low mount height — most compact option
- ADM Auto Lock quick-detach lever; return-to-zero
- 6061-T6 aluminium, Type III hardcoat; ~2.3 oz; USA-made
Technical Specifications
| Fits |
Holosun 509T footprint |
| Mount |
Picatinny (Auto Lock QD) |
| Height |
Low |
| Material |
6061-T6, Type III hardcoat |
| Weight |
~2.3 oz |
| MPN / UPC |
AD-509T-L-STD / 810008517789 |
What's Included
- American Defense AD-509T QD mount (low), mounting hardware
UK Delivery & Support
UK-stocked and dispatched tracked from our UK warehouse — no import duties or customs delays — backed by UK-based support and ADM's lifetime warranty.
Frequently Asked Questions
Which optics fit?
Optics using the Holosun 509T footprint (e.g. HE509T / HS509T).
Which height should I choose?
Low is the most compact; absolute co-witness aligns with AR irons; lower-1/3 sits slightly higher.
Does it return to zero?
Yes — the Auto Lock QD lever gives repeatable return-to-zero.
