Quarter Circle 10 .40 S&W Barrels

Quarter Circle 10 is proud to offer the best .40 S&W barrels available for the AR-15 platform. All our barrels are made right here in our shop from the finest materials available, and feature hand-polished feed ramps and chambers. We turn, chamber, and thread each barrel to exacting tolerances, and all QC10 .40 S&W barrels are threaded for the attachment of flash hiders, suppressors*, and accessories, and finished with a nearly indestructible protective treatment. Our barrels have a medium outer profile and come in a variety of lengths to suit any need. Our .40 S&W barrels feature:

• 4140 Chrome-Moly steel
• 1-in-10″ twist rate
• 5/8-24 or .578-28 threading
• Melonite nitrocarburized protective layer
• .75″ (medium) profile

Now, the modularity of the AR-15 platform can be easily combined with the light weight, easy availability, and broad selection of the .40 S&W cartridge. Whether for home-defense, law enforcement, competition, or plinking, Quarter Circle 10 has you covered, with our philosophy of Made For- Not Modified. Each of our parts is engineered and manufactured with pistol-calibers in mind, rather than modified from rifle-caliber components as an afterthought. We’re Quarter Circle 10, the AR Pistol-Caliber brand.

Note: Our barrels are measured from the end of the muzzle to the end of the breech/feed ramp. Approximately 1″ of the barrel rests inside the upper receiver upon installation, resulting in an installed length of 1″ less than listed overall length.