The ATI MilSport is a semi-automatic rifle chambered in .450 Bushmaster, built on an AR-pattern platform with an aluminum receiver and black Parkerized finish. At 5.2 lbs it is lighter than most rifles in this caliber class. 
 

Key Specifications 

• Brand: ATI 
• Model: Mil-Sport 
• Caliber: .450 Bushmaster 
• Barrel Length: 16 inches 
• Capacity: 5+1 rounds 
• Action: Semi-Auto 
• Sights: Picatinny Rail (no standard sights included) 
• Weight: 5.2 pounds 
• Finish: Black Parkerized 
• Receiver Material: Aluminum 
• Twist Rate: 1:24" 
   

Detailed Features 

 
The .450 Bushmaster delivers substantial terminal performance in a package that fits standard AR lowers, which is the main reason this caliber exists — deer hunting in states with straight-wall cartridge requirements, and hog hunting where stopping power matters at woods distances. 
 
The Picatinny rail across the top lets shooters mount whatever optic suits the application, whether a low-power variable or a simple red dot. There are no iron sights included. The semi-auto action gives faster follow-up shots than a bolt gun, though the 5+1 capacity reflects the .450 Bushmaster's larger case diameter. 
 
The aluminum receiver keeps weight down. The Parkerized finish is serviceable in wet field conditions. 
 

Usage Scenarios 

 
The MilSport in .450 Bushmaster is primarily a hunting rifle — deer, hogs, and similar game at ranges where the big bore's trajectory is not a liability. It also works for range use where the .450 Bushmaster's recoil characteristics are part of the practice session.

Owners of the ATI MilSport in .450 Bushmaster generally give it positive marks for reliability and value at its price point. The .450 Bushmaster stopping power gets consistent praise from hunters, and accuracy reports at typical hunting distances are good.

Build quality is described as solid overall, though a few users note minor fit and finish issues or components they would replace for a cleaner setup. The platform is easy to customize since it follows standard AR conventions, and owners discuss optic choices and accessories as natural next steps.

The main practical complaints are about .450 Bushmaster ammunition availability and cost. It is less common than .223 or .308, which matters for practice-volume shooters. Ergonomics get mixed feedback — the weight and balance work fine for most, but some wish for a different stock option.

Customer service experiences with ATI vary in reported discussions. Most users describe satisfactory support; a smaller number mention delays. Worth knowing before buying.