AeroPrecision121688555
Aero Precision APAR501603AC Assembled Receiver Multi-Caliber 7075-T6 Aluminum Black Anodized Receiver for AR-15$124.99
Availability: In Stock
Current Stock: Out of stock
The ATI Lower AR-15 Mil-Sport Aluminum Stripped Multi-Caliber Receiver is a forged aluminum lower receiver built to mil-spec standards, designed for builders who want a proven foundation for an AR platform rifle. This stripped receiver gives you a clean slate to assemble a custom AR-15 in your choice of caliber, whether you're building a 5.56 NATO hunting rifle, a 300 Blackout pistol, or exploring other multi-caliber configurations that share the AR-15 platform. Since it arrives without fire control group, stock, or grip, you'll have complete control over every component that goes downrange.
American Tactical Imports engineered this lower to mil-spec dimensions, which means it will accept standard AR-15 parts and components from the thousands of manufacturers in the ecosystem. That compatibility is your real advantage: you're not locked into a proprietary system or limited parts availability. Whether you're a first-time builder looking for a reliable starting point or an experienced gunsmith stocking lowers for customer builds, a mil-spec aluminum receiver is the core of countless successful rifles.
The multi-caliber design means one lower can serve as the foundation for multiple upper assemblies—swap uppers to change calibers without buying a whole new rifle. That flexibility makes sense for hunters who might want to run the same platform across different game or seasons, or for shooters who want to experiment with caliber options without the cost and safe-queens problem of building separate guns.
| Product Type | Stripped Lower Receiver |
| Platform | AR-15 |
| Material | Forged Aluminum |
| Standard | Mil-Spec |
| Caliber Compatibility | Multi-Caliber (platform supports various uppers) |
| Manufacturer | American Tactical Imports |
This is a multi-caliber platform lower, which means it will accept AR-15 uppers in various calibers—5.56 NATO, .308 Winchester, 300 Blackout, 6.5 Creedmoor, and others. The lower itself isn't caliber-specific; the caliber is determined by the upper assembly you pair with it. Swap uppers to change calibers on the same lower.
Yes. The ATI Lower AR-15 is built to mil-spec standards, which means it will work with standard mil-spec fire control groups, stocks, grips, and other components from any major AR-15 parts manufacturer. Mil-spec compatibility is a huge advantage when building—you have access to thousands of quality options.
This is a stripped receiver, which means it comes without a fire control group, safety selector, stock, or grip. You'll need to source and install a complete trigger assembly (fire control group), select a stock and grip to suit your build, and add a safety selector. Many builders source these as a complete lower parts kit for convenience.
Yes—that's the advantage of the multi-caliber design. One lower can serve as the receiver for multiple uppers in different calibers, letting you build the same platform in 5.56, .308, 300 Blackout, or other calibers without purchasing additional lowers.
SKU: 120916913 • Weight: 0.6oz
Availability: In Stock
Current Stock: Out of stock
The ATI Lower AR-15 Mil-Sport Aluminum Stripped Multi-Caliber Receiver is a forged aluminum lower receiver built to mil-spec standards, designed for builders who want a proven foundation for an AR platform rifle. This stripped receiver gives you a clean slate to assemble a custom AR-15 in your choice of caliber, whether you're building a 5.56 NATO hunting rifle, a 300 Blackout pistol, or exploring other multi-caliber configurations that share the AR-15 platform. Since it arrives without fire control group, stock, or grip, you'll have complete control over every component that goes downrange.
American Tactical Imports engineered this lower to mil-spec dimensions, which means it will accept standard AR-15 parts and components from the thousands of manufacturers in the ecosystem. That compatibility is your real advantage: you're not locked into a proprietary system or limited parts availability. Whether you're a first-time builder looking for a reliable starting point or an experienced gunsmith stocking lowers for customer builds, a mil-spec aluminum receiver is the core of countless successful rifles.
The multi-caliber design means one lower can serve as the foundation for multiple upper assemblies—swap uppers to change calibers without buying a whole new rifle. That flexibility makes sense for hunters who might want to run the same platform across different game or seasons, or for shooters who want to experiment with caliber options without the cost and safe-queens problem of building separate guns.
| Product Type | Stripped Lower Receiver |
| Platform | AR-15 |
| Material | Forged Aluminum |
| Standard | Mil-Spec |
| Caliber Compatibility | Multi-Caliber (platform supports various uppers) |
| Manufacturer | American Tactical Imports |
This is a multi-caliber platform lower, which means it will accept AR-15 uppers in various calibers—5.56 NATO, .308 Winchester, 300 Blackout, 6.5 Creedmoor, and others. The lower itself isn't caliber-specific; the caliber is determined by the upper assembly you pair with it. Swap uppers to change calibers on the same lower.
Yes. The ATI Lower AR-15 is built to mil-spec standards, which means it will work with standard mil-spec fire control groups, stocks, grips, and other components from any major AR-15 parts manufacturer. Mil-spec compatibility is a huge advantage when building—you have access to thousands of quality options.
This is a stripped receiver, which means it comes without a fire control group, safety selector, stock, or grip. You'll need to source and install a complete trigger assembly (fire control group), select a stock and grip to suit your build, and add a safety selector. Many builders source these as a complete lower parts kit for convenience.
Yes—that's the advantage of the multi-caliber design. One lower can serve as the receiver for multiple uppers in different calibers, letting you build the same platform in 5.56, .308, 300 Blackout, or other calibers without purchasing additional lowers.
SKU: 120916913 • Weight: 0.6oz