The ATI Outdoors Upper 300 AAC 16" Blackout Mil Sport complete AR-15 upper is built for shooters who want a short-stroke, subsonic-capable platform without the complexity of a full custom build. This is a complete upper receiver assembly in 300 Blackout—drop it onto your existing AR-15 lower, and you're ready to run. The 16-inch black nitride barrel balances maneuverability with velocity, making it a solid choice for hunters pushing subsonic rounds through a suppressor or shooters stacking precision at intermediate distances.

300 Blackout has earned its place in the AR platform world because it does two things very well: it runs reliably suppressed at subsonic velocities, and it delivers serious energy in short-barrel carbines. The ATI Mil Sport upper delivers on both counts. The black nitride finish on the barrel resists corrosion and handles abuse, and the complete upper assembly means you're not hunting for compatible parts or wondering about headspace—it ships ready to function.

Whether you're building a truck gun, a backyard plinker, or a hog-hunting rig, a 300 Blackout upper gives you flexibility that intermediate rifle cartridges can't match. Keep it running subsonic for stealth, or switch to supersonic loads for range and power. The 16-inch length keeps the platform handy without sacrificing too much on the ballistic end.

The ATI Outdoors Upper 300 AAC 16" Blackout Mil Sport complete AR-15 upper is built for shooters who want a short-stroke, subsonic-capable platform without the complexity of a full custom build. This is a complete upper receiver assembly in 300 Blackout—drop it onto your existing AR-15 lower, and you're ready to run. The 16-inch black nitride barrel balances maneuverability with velocity, making it a solid choice for hunters pushing subsonic rounds through a suppressor or shooters stacking precision at intermediate distances.

300 Blackout has earned its place in the AR platform world because it does two things very well: it runs reliably suppressed at subsonic velocities, and it delivers serious energy in short-barrel carbines. The ATI Mil Sport upper delivers on both counts. The black nitride finish on the barrel resists corrosion and handles abuse, and the complete upper assembly means you're not hunting for compatible parts or wondering about headspace—it ships ready to function.

Whether you're building a truck gun, a backyard plinker, or a hog-hunting rig, a 300 Blackout upper gives you flexibility that intermediate rifle cartridges can't match. Keep it running subsonic for stealth, or switch to supersonic loads for range and power. The 16-inch length keeps the platform handy without sacrificing too much on the ballistic end.