The American Tactical Mil-Sport AR15 is a semi-automatic rifle chambered in .300 AAC Blackout (7.62x35mm) with a 16-inch barrel and 30+1 capacity. It weighs 5 lbs. 
 

Key Specifications 

• Caliber: .300 AAC Blackout (7.62x35mm) 
• Barrel Length: 16 inches 
• Capacity: 30+1 rounds 
• Weight: 5 lbs 
• Action Type: Semi-Automatic 
• Finish Color: Black 
• Manufacturer: American Tactical Imports 
• Model Number: G15MS300MLP3P 
   

Features 

 
The adjustable Alpha Stock lets you set the length-of-pull to your preference. The Picatinny rail provides a full-length mounting surface for optics and accessories. The 1:8" barrel twist rate stabilizes a wide range of .300 Blackout bullet weights, from 110-grain supersonic loads to 220-grain subsonic loads for suppressor use. The standard trigger is a mil-spec design. 
 
At 5 lbs. the Mil-Sport is on the lighter end of .300 Blackout ARs, which matters for users who move around while shooting. 
 

Usage 

 
The .300 AAC Blackout cartridge is optimized for AR-15-sized rifles and runs in standard AR lowers with a simple barrel swap. It works well for home defense, hunting medium game at moderate ranges, and suppressed shooting -- the subsonic loads run very quietly through a can. The 1:8" twist handles both supersonic and subsonic loads without switching barrels.

The AT Mil-Sport in .300 AAC Blackout draws buyers primarily interested in the cartridge -- the AR platform support here is the vehicle, and the .300 Blackout discussion dominates the feedback.

The caliber's versatility is the most praised attribute. Owners who run the Mil-Sport for home defense, suppressed use, or hunting appreciate that one rifle handles supersonic and subsonic loads without modification. The 1:8" twist is well-matched to the cartridge's bullet weight range.

Build quality feedback is divided. Some owners find it solid and reliable for the price; others mention minor fit-and-finish inconsistencies or quality control variations. The standard trigger gets mixed reviews -- functional but not refined, and aftermarket upgrades are common among owners who shoot it regularly.

Pricing discussions compare it to other budget .300 Blackout options, where it generally sits competitively. Complaints occasionally mention finding better-quality ARs for similar money if caliber flexibility isn't a priority. Reliability with suppressed subsonic loads is noted positively by owners running cans.