Apex 9mm Drop-In Threaded Barrel for FN 509

If you’ve been wanting to run a suppressor on your FN 509, the biggest holdup is usually the barrel. Factory barrels aren’t threaded, so you’re stuck with the muzzle blast. This drop-in threaded barrel from Competition Trigger Works solves that problem. It’s made specifically for the FN 509 platform, so you can mount your favorite suppressor or compensator without any guesswork. Just swap it in, thread on your muzzle device, and you’re ready to shoot suppressed.

Will this fit my gun?

• FN 509 (full-size)
• FN 509 Compact
• FN 509 Midsize
• FN 509 Tactical (factory threaded models—this barrel works as a replacement or spare)
• FN 509 LS Edge
• Does NOT fit FN 509C or 509MRD without verifying barrel lug engagement—please check your slide

Key features

• Drop-in fit – No fitting, no filing, no gunsmithing. Remove your factory barrel, install this one, and you’re done.
• 1:10” twist rate – Stabilizes typical 9mm loads from 115gr to 147gr without issue.
• 1/2-28 threaded muzzle – The standard thread pitch for most 9mm suppressors and compensators.
• Heat-treated steel – Durable black finish holds up to holster wear and range time.
• Thread protector included – Captive O-ring keeps it snug when you’re not running a can.
• Made in the USA – Quality you can count on.

Install difficulty: 1 out of 5

This is about as easy as it gets. Field-strip your FN 509, push out the slide takedown pin, remove the factory barrel, drop in the new one, and reassemble. Tools needed: none (maybe a small punch if the slide pin is tight, but 99% of the time you can do it by hand).

Frequently asked questions

Will this work with my suppressor?

If your suppressor uses a 1/2-28 piston or direct-thread mount, yes. The barrel is threaded to that standard, so most 9mm suppressors from SilencerCo, Dead Air, Rugged, etc., will thread right on.

Can I use this barrel without a suppressor?

Absolutely. The included thread protector covers the threads when you’re not running a can. It’s a drop-in upgrade either way—nothing forces you to shoot suppressed.

Does this barrel affect reliability?

We’ve tested these with a variety of factory ammo (115gr, 124gr, 147gr) and they run fine. Because it’s a drop-in fit, your slide and recoil spring don’t need changes. If you have a very tight chamber preference, a quick polish might help, but we haven’t found it necessary.

Important shipping note: We cannot ship this barrel to CA, CT, DE, Washington DC, HI, IL, NY, or WA. Please check your local laws before ordering. All orders ship within 1–2 business days, and we stand behind every barrel with our standard warranty—if it’s defective or doesn’t fit your FN 509, we’ll make it right.