TacFire Lower Parts Kit — .223 Rem / 5.56×45 NATO | Unassembled AR Platform — Aluminum — SSRK556LPK • UPC: 745559515239
Build smarter, customize faster, and finish your AR project with confidence. The TacFire Lower Parts Kit for .223 Rem / 5.56×45 NATO (SSRK556LPK) is an unassembled, parts-only kit designed for AR-platform lowers. Machined aluminum components and a carefully selected parts set give builders a lightweight, durable foundation for hunting, range, competition, or duty-style rifles. Optimized for compatibility and finished with attention to fit, this kit is a reliable choice whether you’re finishing a new lower or replacing worn parts.
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Product Overview
The TacFire SSRK556LPK lower parts kit provides the essential internal parts needed to assemble a functional AR lower receiver in .223 Rem or 5.56×45 NATO. Carefully selected to balance durability, weight, and value, this kit uses aluminum where appropriate to reduce overall weight while maintaining strength at common wear points. It’s a no-frills, high-value option for builders who want core lowering components that integrate cleanly with standard AR-15 style lowers and compatible components.
Key Features & Benefits
Caliber Compatibility: Designed for .223 Rem / 5.56×45 NATO platforms—ideal for standard AR-15 style builds.
Lightweight Aluminum Components: Aluminum construction on primary parts helps reduce weight without sacrificing structural integrity for non-stress pins and levers.
Standardized Threading (1/2"-28 tpi): Includes components compatible with common .223/5.56 muzzle threading conventions where applicable—helpful for ensuring accessory compatibility down the line.
Unassembled, Parts-Only Kit: Ideal for builders who prefer to fit and install parts themselves or through a qualified gunsmith. No assembly instructions included—keeps the kit manufacturer-neutral and builder-friendly.
Precision Fit: Manufactured to common AR platform tolerances for smooth fitment with mil-spec and commercial lowers.
Cost-Effective Replacement or Upgrade: A practical choice to refresh an aging lower or to complete a custom build without paying for features you don’t need.
What’s Included (Typical Contents)
Exact contents may vary between production runs—always verify packaging for final checklist.
Trigger and sear components (unassembled)
Hammer, disconnector, and associated springs (unassembled)
Bolt catch components
Selector (safety) lever and detent
Magazine catch and spring
Takedown/pivot pins and detents
Miscellaneous springs, pins, and small hardware needed to operate a standard AR lower
Compatibility & Fit Notes
Platform: AR-15 style lower receivers (designed for standard .223 Rem / 5.56 NATO configuration).
Works With: Standard mil-spec and many commercial lower receivers; magazine compatibility follows normal .223/5.56 standards.
Before You Buy: Confirm your lower receiver spec (mil-spec vs. commercial) and ensure the rest of your parts (trigger housing, grip, buffer assembly, etc.) are compatible. If unsure, consult a qualified gunsmith.
Performance & Practical Advantages
Reliable Functionality: All core mechanical components are chosen for dependable engagement and repeatability when properly installed and maintained.
Ease of Customization: Unassembled format lets you choose trigger springs, polish, or aftermarket enhancements to tune pull weight or feel—without being locked into a finished assembly.
Weight Savings: Aluminum components where used reduce overall carry weight compared to an all-steel kit, beneficial for hunting and long-range carry scenarios.
Who Should Buy This
Hobbyist builders completing a custom .223/5.56 AR rifle.
Gunsmiths and armory shops stocking a reliable lower parts kit for repairs and customer builds.
Shooters replacing worn internal parts while keeping costs low.
Competitive shooters or weekend range enthusiasts who want to tailor trigger characteristics or internals.
Safety, Legal & Installation Notes
Legal Compliance: Firearms laws and assembly rules vary significantly by region. Confirm federal, state, and local regulations before purchasing or assembling any firearm components. This product is intended for lawful, responsible use only.
No Assembly Instructions Provided: This kit is sold unassembled. Do not attempt critical fitting, headspace checks, or final safety verification without appropriate expertise. For safety and legal reasons, have a qualified gunsmith perform installation, inspection, and testing if you are not fully trained.
Use Responsibly: Proper installation, function checks, and safe handling procedures are essential. This description intentionally avoids step-by-step assembly guidance.
Technical Specifications (High-Level)
Model / SKU: SSRK556LPK
UPC: 745559515239
Caliber: .223 Rem / 5.56×45 NATO (platform compatibility)
Platform: AR-15 / AR-style lower receiver parts kit (unassembled)
Material Highlights: Machined aluminum components (select parts), steel springs and critical engagement surfaces where required
Thread Reference: 1/2"-28 tpi referenced for .223/5.56 conventions
Buying Tips & Final Considerations
Verify the exact parts list with the retailer before purchase if you require specific components.
For matched trigger performance, consider pairing this kit with a quality aftermarket trigger group—but remember this kit is unassembled and intended for custom installation.
If building for competition or critical use, budget for a gunsmith inspection and break-in period to ensure long-term reliability.
Summary
The TacFire Lower Parts Kit SSRK556LPK (UPC: 745559515239) is a practical, cost-conscious solution for builders and gunsmiths working on .223 Rem / 5.56 NATO AR-platform rifles. With a focus on lightweight materials, standardized compatibility, and core mechanical reliability, this unassembled kit gives you the flexibility to finish, tune, or repair an AR lower while keeping control of final assembly and performance choices.
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