This steel optic mount adapts the Holosun 509T to any SIG P320 slide with the SIG-LOC optic cut. It solves two problems: mounting the 509T to the proprietary SIG-LOC footprint, and keeping carbon off the objective lens. The integrated rear sight sits forward of the optic and doubles as a gas shield, blocking blowback from the ejection port. A tall front sight (included) provides a lower-1/4 co-witness through the 509T window.
Compatibility
- Sig Sauer P320 (all models with SIG-LOC optic cut)
- P320 Legion series
- P320 M17 / M18 (retains factory Loaded Chamber Indicator function)
- Holosun 509T (any generation)
- Not compatible with standard Delta Point Pro / RMR-cut slides
Key Features
- Machined from billet steel, black oxide finish
- BUIS base serves as gas shield — deflects debris away from optic glass
- Rear sight co-witnesses in bottom 25% of 509T window
- Tall front sight included; two height options based on barrel length
- Thread-locking patch pre-applied to screws — torque to 20 in-lb
- Sights regulated for POA=POI at 10 yards with 115 Gr. ammunition
- Rear-sight-behind-optic version available (includes blast deflector not visible through glass)
Install Difficulty: 3/5
Requires slide disassembly, removal of factory optic cover plate, and screw torque wrench. Standard gunsmith tools (punch set, non-marring hammer, torque driver). Expect 20–30 minutes for experienced users. Loctite pre-applied — no additional adhesive needed.
FAQ
Will this work on a P320 X-Five?
Only if the slide has the factory SIG-LOC cut. X-Five models with the standard RMR/DPP cut require a different adapter plate. Verify your slide’s footprint before ordering.
Does the rear sight hold zero?
Yes. The sight is machined into the mount body — no set screws or drift adjustments. Windage is fixed; elevation is set at the factory. Use the optic’s reticle for zero.
Can I use suppressor-height sights instead of the included front?
The included front sight is matched to the mount’s rear notch height. Substituting a different front sight will shift the co-witness point. If you need a different height, contact us for the appropriate option.
Shipping: Ships within 1 business day. Warranty: Lifetime warranty against manufacturing defects. No-hassle returns within 30 days of receipt.
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