The Holosun 509PLT-FNX45 is a steel adapter plate that carries a 509 footprint enclosed sight on the factory optic cut of an FNX-45 Tactical slide.
The 509 series uses a rear-lug footprint of Holosun's own, which does not match a factory RMR or RMSc cut. This plate is the piece that bridges the gap, and it is the only reason the two ever meet.
Holosun make it in steel with a corrosion-resistant finish, and both sets of fasteners come with it: the screws that hold the plate down to the slide, and the screws that hold the sight down to the plate. That matters more than it sounds, because a plate arriving without the second set is the most common way one of these ends up in a drawer. Holosun do not publish a weight for the plate.
On the pistol side it is cut for FNX-45 Tactical slides that left the factory optics-ready. On the optic side it takes the 509 footprint — the HS509T X2, the HE509T X2 and the HE509T-X2-GD. Be clear about what it does not do: an RMR-pattern sight such as a 507C or 407C will not sit on it, and neither will an RMSc-pattern 507K or 407K. Those are different bolt spacings and different lug arrangements, not a matter of forcing the screws.
Why shooters choose the 509PLT-FNX45
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Optic footprint — Holosun 509 rear-lug pattern — HS509T X2, HE509T X2 and HE509T-X2-GD
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Host — FNX-45 Tactical slides with the factory optic cut
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Material — steel with a corrosion-resistant finish
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Hardware — plate-to-slide and optic-to-plate screws supplied together
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Not compatible — RMR-pattern sights such as the 507C, or RMSc-pattern sights such as the 507K
What the 509PLT-FNX45 fits
One slide, one footprint: FNX-45 Tactical to Holosun 509. For other hosts, Holosun make the same plate for the FN 509 Tactical, the Glock MOS 9mm and the CZ P10, plus a version for 507C and RMR-cut slides. If the 509T is going on a rail rather than a slide, the 509T Picatinny mount is the part you want.
Specifications
| Type |
Optic adapter plate |
| Optic footprint |
Holosun 509 (509T) |
| Fits |
FNX-45 Tactical optics-ready slides |
| Material |
Steel, corrosion-resistant finish |
| Hardware |
Plate-to-slide and optic-to-plate screws included |
| Brand |
Holosun |
| MPN |
509PLT-FNX45 |
A small part, but the one that decides whether the sight goes on at all. Order the 509PLT-FNX45 today — imported from the USA with all duties paid by us and dispatched tracked from the UK in 7–10 business days, with nothing to pay on delivery.
Explore more: Optic Mounts, 509 Plate for RMR-Cut Slides or browse all Holosun.
