The Alex Pro Firearms (APF) SF-15 is an AR-15 style semi-automatic rifle chambered in 5.56mm NATO, manufactured by Alex Pro Firearms in Minnesota. Specific configurations can vary, but generally, it is built with high-quality, in-house components and offers reliable performance. Key Specifications (Typical Configuration): Note that Alex Pro Firearms offers various models, and components may differ between specific "SF-15" (or "APF-15") variants such as the "Valor-15", "Fury-15", or "Guardian". The following specifications are representative of common 5.56 NATO rifle models: Caliber: 5.56mm NATO (also safely accommodates .223 Remington). Action: Semi-automatic, Direct Impingement gas system. Barrel Length: Typically 16 inches, though other lengths are available in different models (e.g., SBR or pistol versions). Barrel Material/Finish: Usually 4150 Chrome Moly Vanadium (CrMoV) steel with a Nitride or Phosphate finish. Barrel Twist Rate: Commonly 1:7 or 1:8 twist rate, suitable for a wide range of bullet weights. Gas System: Carbine or mid-length gas system, depending on the specific configuration. Handguard: Free-floating M-LOK rail (typically 15 inches or 15.5 inches) for accessory attachment. Receiver Material: Forged 7075 Aluminum upper and lower receivers. Trigger: Often features an upgraded APF 4.5 lb. drop-in single-stage trigger, better than a standard mil-spec trigger. Stock: M4 style adjustable or a B5 Systems stock, depending on the model. Grip: A2 style or Magpul MOE pistol grip. Sights: Optics ready; typically includes a full-length Picatinny top rail but no included iron sights. Muzzle Device: A2 Birdcage flash hider. Finish: Available in various Cerakote finishes, including black, Flat Dark Earth, and others. User and Expert Opinions: Quality & Durability: Reviewers consider APF rifles to be a good quality build, made with premium components in the USA. Performance: The rifles are praised for shooting smoothly and for their accuracy, with many achieving sub-MOA accuracy in testing. Trigger: The upgraded drop-in trigger is frequently mentioned as a standout feature, providing a crisp and clean pull. Versatility: They are considered versatile firearms suitable for a variety of uses, including target shooting, hunting, home defense, and law enforcement duty. OYS