FN 509M 9mm | 4.5″ Barrel | Tritium Sights

The FN 509M is a mid-size, duty-rated 9mm semi-automatic pistol designed for consistent trigger feel and reliable sighting in low light. It features a flat-faced trigger and a conical striker intended to reduce trigger pull weight, along with three-dot tritium night sights for low-light acquisition. For a compact red-dot option that pairs well with this platform and remains under $1,000, consider the Trijicon RMR; it maintains a low profile and proven durability on mid-size service pistols.

Applications: duty or professional carry and range training/qualification.

Product Specifications

• The manufacturer is listed as FN America / FN Herstal.
• The model designation is FN 509M.
• The caliber is 9mm.
• The action is described as Double Action.
• The barrel measures 4.5 inches for a balance of sight radius and concealability.
• The overall length is 7.4 inches.
• The unloaded weight is listed as 26.5 ounces.
• Sights are specified as fixed three-dot tritium night sights for low-light use.
• Magazine capacity per magazine is listed as 15 rounds.
• Included factory magazines are reported as two or three 15‑round magazines; see notes.
• The trigger features a flat-faced design intended for a consistent break.
• Slide features front and rear cocking serrations for positive slide manipulation.
• The product is described in one source as the Law Enforcement 509 variant with duty-oriented upgrades.
• The UPC is 845737013783.

The FN 509M presents a pragmatic balance of sight radius, trigger ergonomics, and night-sight capability for professionals and serious recreational shooters. Its mid-size footprint and 4.5″ barrel make it well suited to controlled-range work and duty carry scenarios where consistent performance and reliable sighting are priorities. Consider mounting a compact red-dot to take full advantage of the platform’s sighting improvements and to speed target acquisition during day and night-use.

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