Holosun 407/507K Adapter for FN 509

Holosun 407/507K Adapter for FN 509 is a pistol optic mounting adapter designed to allow Holosun 407K and 507K series micro red dots to be installed on FN 509 pistols. This adapter provides a secure, repeatable interface that bridges the footprint differences between the compact Holosun K-series optics and the FN 509 slide, enabling reliable slide-mounted optic use without permanent modification.

Produced by Holosun, this adapter addresses a common fitment challenge for shooters who want to run a smaller, lighter micro red dot on the FN 509 platform. The design focuses on durability and alignment consistency, making it suitable for pistols configured for duty use, range training, or everyday carry, where a compact optic and solid mounting solution are required.

Key Features

• Designed to mount Holosun 407K and 507K series optics

• Specifically fitted for FN 509 pistols

• CNC-machined construction for precise fit and repeatability

• 6061 aircraft-grade aluminum for strength with controlled weight

• Type III hard-anodized finish for improved wear and corrosion resistance

• Black finish to match common slide and optic finishes

• Passive mechanical adapter with no power or electronics

Specifications & Construction

• Product Type: Optic adapter / mounting accessory

• Compatible Optics: Holosun 407K, Holosun 507K

• Host Platform: FN 509 pistols (as specified)

• Material: 6061 aircraft-grade aluminum

• Manufacturing Method: CNC machined

• Finish: Type III hard anodized

• Color: Black

• Dimensions / Weight: Not specified in provided product data

The CNC-machined aluminum body is intended to maintain consistent optic alignment under recoil, while the hard-anodized surface helps resist wear from repeated mounting and long-term use.

Compatibility & Intended Use

This adapter is explicitly intended for use with Holosun 407K and 507K series optics on FN 509 pistols. It is not described as compatible with other Holosun optic families or pistol platforms.

Typical applications include:

• FN 509 pistols set up for duty or service use

• Range and training pistols using compact micro red dots

• Everyday carry configurations where reduced optic size and weight are preferred

Users should confirm that their optic is part of the Holosun 407K/507K series before installation and follow recommended mounting and torque procedures.

What’s Included

• One (1) Holosun 407/507K Adapter for FN 509

• Manufacturer packaging and documentation

The Holosun 407/507K Adapter for FN 509 provides a straightforward, durable solution for mounting compact Holosun micro red dots on the FN 509 platform, supporting reliable optic integration for training, carry, or duty-oriented pistol setups.