Description
The Knights Armament Company SR-30 Lower Receiver Assembly is a premium, purpose-built foundation for a 300 Blackout AR-15. It’s the dedicated lower half of KAC’s legendary SR-30 system, designed from the ground up for optimal performance with subsonic and supersonic .300 BLK ammunition. This isn’t just a marked-up mil-spec lower; it’s the heart of a suppressed-ready platform that I’ve built several uppers for, and it always delivers a flawless interface. At $908.31, it’s an investment in proven reliability and seamless integration for your next high-end build.
Key Features
- Factory-built by Knights Armament Company for the SR-30/300 Blackout platform.
- Includes KAC’s proprietary two-stage trigger, ambidextrous safety selector, and magazine catch.
- Machined from 7075-T6 aluminum forgings with a hardcoat anodized black finish.
- Marked and configured specifically for the .300 AAC Blackout cartridge.
- Mil-spec compatible with most AR-15 upper receivers, ensuring broad build flexibility.
- Drop-in ready assembly—no gunsmithing required to start your build.
Specifications & Details
| Specification | Detail |
|---|---|
| Manufacturer | Knights Armament Company (KAC) |
| Model | SR-30 Lower Receiver Assembly |
| Caliber | .300 AAC Blackout |
| Frame Material | 7075-T6 Aluminum |
| Finish | Hardcoat Anodized, Black |
| Trigger | KAC 2-Stage Match Trigger |
| Fire Control | Ambidextrous Safety Selector |
Look, the devil is in the details, and KAC sweats every one. The lower is marked for .300 BLK, which is more than just engraving—it’s a commitment to the platform’s specific needs. The included two-stage trigger breaks cleanly at around 4.5 pounds, a massive upgrade over a standard single-stage. The ambi controls are intuitive and robust. Weighing in at approximately 2.5 lbs as an assembled lower, it provides a solid, balanced feel when paired with an upper. This assembly ships to Missouri and compliant US states, ready for your FFL to complete the transfer.
Who This Is For
This is for the builder who understands that the lower is the brain of the rifle, not just a housing. It’s for someone building a dedicated, no-compromise 300 Blackout rifle, especially one intended for use with a suppressor. If you’re pairing it with a KAC SR-30 upper, you’re getting a factory-correct match. But it’s also perfect for someone wanting the KAC trigger and control feel under a high-quality upper from another maker like Daniel Defense or BCM. You’re paying for seamless function and top-tier components, not just a name.
Straight Talk: Pros & Cons
Pros: The out-of-the-box experience is superb. You get a complete, tuned system with a fantastic trigger and ambi controls installed. The fit and finish are exactly what you expect from KAC—impeccable. It’s the definitive starting point for a serious 300 BLK build. Compatibility is broad; I’ve mated it with several non-KAC uppers with zero issues.
Cons: The price is the most obvious hurdle. This is a premium component for a premium build. Also, because it’s a complete assembly, you’re buying the KAC trigger whether you want it or not—though most will see that as a benefit.
Frequently Asked Questions
Q: Is this a complete firearm?
A: No. This is a Firearm Receiver, often called a “lower.” It is the serialized part that, by law, requires an FFL transfer for firearm purchases. It comes fully assembled with trigger, grip, and stock, but you must attach a compatible upper receiver assembly and magazine to make a functioning rifle.
Q: Will this work with any standard AR-15 upper in 5.56 NATO?
A: Mechanically, yes—it’s mil-spec compatible. However, it is specifically marked and intended for .300 AAC Blackout. Using it with a 5.56 upper is possible but goes against its designed purpose and could cause confusion, which is a safety concern. Always verify your caliber.
Q: Does it come with a magazine?
A: Typically, KAC lower assemblies do not include a magazine. You will need to source .300 Blackout specific magazines, which are often standard USGI mags but dedicated ones from brands like Magpul are recommended for optimal feeding reliability.
Here’s the thing—if you’re building a 300 Blackout rifle where reliability is non-negotiable, starting with the right foundation is everything. The KAC SR-30 Lower Assembly eliminates guesswork and provides a proven, professional-grade core. This component is available at firearms-missouri.com for Missouri residents and nationwide. See our product page for current availability and to start the process with your local FFL.
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