Accuracy International Chassis Systems bring ergonomic and functional benefits that are delivered with degrees of modularity and configurability that cannot be achieved with any traditional stock. AI pre-fits are available for both 27mm and 30mm tenon sizes. Up to 64% lighter than traditional steel barrels of similar contour. Improved heat dissipation for cooler and longer lasting barrels. Wrapped with high-strength, aerospace-grade carbon fiber impregnated with a proprietary matrix resin. PROOF Research Pre-Fit Accuracy International barrels are quick and easy to install on the AI platform and require no specialized gunsmithing. PROOF Research drop-in barrels fo Mfg: Proof Research