The Radical Firearms FP-10.5 is a specific variant of the Radical Firearms AR-15 platform with a 10.5-inch barrel length. It is an AR-15 rifle chambered in 5.56 NATO or .223 Remington. It's designed for compactness and maneuverability, making it suitable for close-quarters or tactical applications. The FP-10.5 features a barrel length of 10.5 inches. This shorter barrel length allows for increased maneuverability and ease of handling in confined spaces. The FP-10.5 is typically chambered in 5.56 NATO or .223 Remington. These calibers offer common compatibility with AR-15 rifles and a wide range of available ammunition. The Radical Firearms FP-10.5 features a direct gas impingement (DGI) gas system. In a direct gas impingement system, gas is tapped from the barrel through a gas port and directed back into the receiver through a gas tube. The gas then impacts a gas key on the bolt carrier group, causing the bolt carrier to unlock, cycle rearward, extract and eject the spent casing, and chamber a new round. The FP-10.5 may include features such as a free-floating handguard, Picatinny top rail for optic attachment, adjustable stock, and various furniture options. These features can vary depending on the specific variant and customization options chosen.