EFK Fire Dragon Pistol Barrels. These Are Some Of The Finest Pistol Barrels Made In The World! Because of the care exercised in manufacturing and our refusal to compromise on any step of the process. The end result is a good-looking, top-quality barrel with consistent, accurate and long-lasting performance. And don't forget the service. We deal with our customers on a personal level to ensure their complete satisfaction on all of our products. All threaded barrels come with a thread protector. Industry standard is 150 rounds to break in a barrel before threading any device on to the barrel. When a barrel contains the word "conversion", it means these barrels work only in 40S&W and .357 converting to 9mm. You cannot go from a 9mm to a 40S&W or 357Sig For best results converting to 9mm from 40 S&W use a 9mm mag. Specifications for EFK Fire Dragon FN 57 MK3/MRD 55in With Adapter Pistol - Barrel - Threaded: Manufacturer: EFK Fire Dragon Color: Stainless Finish: Polished Fabric/Material: Stainless Steel Gun Make: FN Herstal Features of EFK Fire Dragon FN 57 MK3/MRD 55in With Adapter Pistol - Barrel - Threaded Stainless Steel Barrels make for long life and extreemly high durability The finest material available (type 416 Stainless Steel) Machining processes are accomplished on CNC equipment for close-tolerance production Heat treating is done in a vacuum furnace for clean, consistent hardness of 40-42Rc Package Contents: EFK Fire Dragon FN 57 MK3/MRD Threaded 10X1mm RH 55in With Adapter Pistol - Barrel - Threaded Thread Protector