Apex 5.00″ Slide for FN 509 – ACRO/MPS Slide Cut

This is a stripped Apex 5.00″ slide for the FN 509, built for shooters who want a longer sight radius and a proven platform upgrade without paying for parts they already own. You supply the internals from your factory FN 509 slide (extractor, ejector, firing pin, springs, etc.) and a 5″ barrel. All internal spaces in this slide are machined to accept standard factory FN components, so you can swap your existing parts directly over with no fitting required. If you prefer a complete slide assembly, Apex offers a Slide Completion Kit that they will install prior to shipping — but that kit must be purchased with the slide and assembled by Apex. Otherwise, you can buy new factory FN components from Midwestgunworks.com or Brownells.com.

Slide Specs & Fitment: This is a 5″ replacement slide specifically for the FN 509 pistol family. It features aggressive front and rear cocking serrations for positive slide manipulation, even with wet or gloved hands. You have two serration options: Classic (standard vertical serrations) or Lightning Bolt (angled, aggressive cuts). The slide comes with suppressor-height black-on-black sights installed by Apex, so you can co-witness with a red dot or just use the irons out of the box. The finish is a black PVD coating — durable, low-friction, and corrosion-resistant for daily carry or range use.

Ported Slide Option: This slide is also available with port cuts that match the Apex Ported Barrel for the FN 509. The ports align with the barrel ports to vent gasses upward, reducing muzzle rise and keeping the front sight on target during fast strings. Important: The ported slide requires an Apex ported barrel (part number coming soon) to function correctly — standard barrels will not align with the ports.

Optic Cut: The slide is machined with an ACRO footprint cut, allowing direct mounting of optics like the Aimpoint ACRO, Steiner MPS, Pandora PB-3, or any other optic that uses the ACRO mounting standard. No adapter plates needed. When mounting your optic, check the manufacturer’s recommended torque specs. If no recommendation is provided, torque screws to a maximum of 20 in-lb (inch pounds).

Barrel Options: You can use a factory 5″ FN 509 barrel with this slide, or upgrade to one of Apex’s drop-in barrels:

• Direct Drop-In Barrel (105-073) — 5.00″, standard rifling, no threading.
• Drop-In Threaded Barrel (105-074) —