Luth-AR 20 in Bull Barrel Complete Upper Barrel Receiver Assembly Silver/Black 20. The fluted bull barrel profile provides adds strength for stability reducing recoil and increasing accuracy. The barrel is made of high-quality stainless steel providing durability and longevity. The 1-9 twist rate is suitable for stabilizing heavy projectiles. This is an excellent option for shooters who want a heavy barrel with precision shooting in mind. Starts with our 20 in .223 caliber fluted bull barrel made from 416 SST with a 1-9 twist mated to our A3 Flattop receiver which includes our bolt carrier charging handle forward assist and ejection port cover. The upper is then topped off with our lo-profile gas system and our ergonomic 15 in Palm Handguard with KeyMod or M-LOK slots and a Picatinny top-rail. Specifications for Luth-AR 20 in Bull Barrel Complete Upper Barrel Receiver Assembly: Manufacturer: Luth-AR Caliber: .223 Remington Barrel Length: 20 in Color: Silver/Black Attachment Type: Picatinny Handguard Length: 15 in Gun Rail: M-LOK Magazine Included: No Mount Type: Picatinny Package Contents: Luth-AR 20 in Bull Barrel Complete Upper Barrel Receiver Assembly Luth-AR FTBL-B20M: 20 in Bull Barrel Complete Upper Barrel Receiver Assembly Silver/Black 20