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.

Feel free to ask us any question regarding this product.