FN | FN 509 Magazine | 9mm | Black

FN's factory 509 magazine is built from heat‑treated stainless steel with a steel wire internal spring and anti‑tilt polymer follower, holding a genuine 17 rounds standard or 24 in the extended version -⁠- real capacity that's compatible across every full‑size, compact, and subcompact 509 variant. Numbered witness holes give an at‑a‑glance round count, and a polymer floor plate backs long‑term corrosion resistance. The factory‑spec magazine engineered to the exact tolerances the 509's action was actually designed around.