Aero Precision M4E1 pistol-configuration in .300 Blackout with a 10.5-inch barrel. The pistol designation avoids NFA SBR classification while providing a compact suppressor platform. The most popular Aero configuration for .300 BLK suppressor hosts. Type: Rifle Action: Semi-Automatic Caliber: .300 BLK Capacity: 30 Year introduced: 2018, USA Weight: 80 oz Overall length: 23.5" Status: Active Intended use: Suppressor Host, Home Defense, CQB