EFK Fire Dragon 5.5" Threaded Barrel for FN Five-seveN® (IOM, USG, MK2, MRD/MK3)

Upgrade your FN Five-seveN® pistol with a premium 5.5" threaded barrel from EFK Fire Dragon. Precision-machined from high-grade 416R stainless steel, this barrel delivers exceptional accuracy, long-lasting performance, and compatibility across all Five-seveN models, including:

• IOM
• USG
• MK2
• MRD / MK3

Whether you're building a suppressor-ready handgun or improving your Five-seveN’s performance, this barrel is a true drop-in upgrade that requires no fitting or gunsmithing.

Key Features

• Drop-in compatibility with all FN Five-seveN® models (IOM, USG, MK2, MRD/MK3)
• 5.5” length, CNC-machined from 416R stainless steel
• Conventional button rifling, twist rate: 1:9
• Threaded 10mm x 1mm RH – includes free thread protector
• Free adapter: Converts 10x1mm RH to 1/2x28 RH for broader suppressor compatibility
• Heat-treated in a vacuum furnace to 40–42 Rc for clean, consistent hardness
• True drop-in fit – no modification or fitting required
• Made in the USA

Safety Notice: Due to the high velocity of 5.7x28mm rounds, EFK strongly recommends using only new, factory-loaded ammunition. Reloaded ammo is not advised.

Suppressor Compatibility

This barrel is ready for suppressor use right out of the box. The 10x1mm RH thread pattern is ideal for suppressors like the GSL 57-22, and the included 1/2x28 RH adapter expands compatibility to many 5.7-rated silencers and muzzle devices.

Pro Tip: Always verify your suppressor is rated for 5.7x28mm pressure levels before use.

Break-In Recommendation

As with most high-performance barrels, a break-in period is recommended. Industry standard is 150 rounds before attaching any muzzle devices to ensure proper fit and finish of the threads.

Why Choose EFK Fire Dragon?

EFK Fire Dragon barrels are regarded among the finest pistol barrels in the world, thanks to uncompromising quality at every stage:

• Premium 416R stainless steel
• Tight-tolerance CNC machining
• Clean, consistent vacuum heat treatment
• Hand-checked for fit, finish, and performance
• Backed by one of the best lifetime warranties in the industry

Installation Instructions

This is a true drop-in barrel. Just remove your factory barrel and replace it—no fitting or gunsmithing required.

Technical Specs

• Barrel Length: 5.5"
• Thread Pattern: 10mm x 1mm RH
• Adapter Included: Yes – Converts to 1/2x28 RH
• Material: 416R Stainless Steel
• Twist Rate: 1:9
• Rifling Type: Conventional, Button Rifled
• Hardness: 40–42 Rc (vacuum heat-treated)
• Thread Protector: Included