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Availability: In Stock
Building an AR-15 from the ground up gives you control over every detail of your rifle—and that starts with the lower receiver assembly. The TacFire SSRK556LPK unassembled AR-15 lower parts kit provides the individual components you need to complete a .223 Rem/5.56x45mm NATO lower receiver, letting you choose your own lower, trigger group, and final configuration. This is for the builder who wants to understand their platform and customize without compromise.
TacFire's lower parts kits are designed around the mil-spec AR-15 platform and built to tolerances that work with standard parts. The aluminum construction keeps weight down while delivering durability through thousands of rounds. The 1/2"-28 tpi threading ensures compatibility with standard AR-15 muzzle devices and suppressors. Because this kit is unassembled, you're getting raw components—not a pre-installed or fire-control group ready to drop in. That means you have total say in how things go together and what fits your build, whether you're assembling a precision rifle, a duty gun, or a range shooter.
Whether you're a long-time tinkerer or stepping into your first build, having quality components on hand means fewer delays when you're at the bench. TacFire spec parts work well with mainstream aftermarket triggers, stocks, and furniture, so you're not locked into a single ecosystem. Just verify your lower receiver matches the .223 Rem/5.56x45mm platform before you start, and make sure your muzzle brake or suppressor uses the same 1/2"-28 threading.
| Product Name | TacFire SSRK556LPK Unassembled AR-15 Lower Parts Kit |
| Caliber | .223 Rem/5.56x45mm NATO |
| Material | Aluminum |
| Muzzle Threading | 1/2"-28 tpi |
| Platform | AR-15 |
| Condition | Unassembled Components |
This kit is designed for standard mil-spec AR-15 lower receivers chambered in .223 Rem/5.56x45mm NATO. Always verify your lower matches the platform and caliber before assembly. Some specialty or proprietary lowers may have different tolerances or mounting points.
An unassembled kit includes the individual components as separate pieces, not pre-installed in the lower receiver. You'll be doing the final assembly yourself. This gives you control over trigger selection and lets you troubleshoot each part during fitment.
Yes—the 1/2"-28 tpi threading is the mil-spec standard for .223 Rem/5.56x45mm AR-15 rifles. This means compatibility with the vast majority of brakes, flash hiders, and suppressors on the market. Always confirm your muzzle device's threading before purchase.
Yes. This lower parts kit contains the components that install into a lower receiver; it does not include the lower itself. You will need to source a separate AR-15 lower receiver to complete your build.
SKU: 115669232 • Width: 5.5in • Height: 5.4in • Depth: 16.1in • Weight: 6.1oz
Availability: In Stock
Building an AR-15 from the ground up gives you control over every detail of your rifle—and that starts with the lower receiver assembly. The TacFire SSRK556LPK unassembled AR-15 lower parts kit provides the individual components you need to complete a .223 Rem/5.56x45mm NATO lower receiver, letting you choose your own lower, trigger group, and final configuration. This is for the builder who wants to understand their platform and customize without compromise.
TacFire's lower parts kits are designed around the mil-spec AR-15 platform and built to tolerances that work with standard parts. The aluminum construction keeps weight down while delivering durability through thousands of rounds. The 1/2"-28 tpi threading ensures compatibility with standard AR-15 muzzle devices and suppressors. Because this kit is unassembled, you're getting raw components—not a pre-installed or fire-control group ready to drop in. That means you have total say in how things go together and what fits your build, whether you're assembling a precision rifle, a duty gun, or a range shooter.
Whether you're a long-time tinkerer or stepping into your first build, having quality components on hand means fewer delays when you're at the bench. TacFire spec parts work well with mainstream aftermarket triggers, stocks, and furniture, so you're not locked into a single ecosystem. Just verify your lower receiver matches the .223 Rem/5.56x45mm platform before you start, and make sure your muzzle brake or suppressor uses the same 1/2"-28 threading.
| Product Name | TacFire SSRK556LPK Unassembled AR-15 Lower Parts Kit |
| Caliber | .223 Rem/5.56x45mm NATO |
| Material | Aluminum |
| Muzzle Threading | 1/2"-28 tpi |
| Platform | AR-15 |
| Condition | Unassembled Components |
This kit is designed for standard mil-spec AR-15 lower receivers chambered in .223 Rem/5.56x45mm NATO. Always verify your lower matches the platform and caliber before assembly. Some specialty or proprietary lowers may have different tolerances or mounting points.
An unassembled kit includes the individual components as separate pieces, not pre-installed in the lower receiver. You'll be doing the final assembly yourself. This gives you control over trigger selection and lets you troubleshoot each part during fitment.
Yes—the 1/2"-28 tpi threading is the mil-spec standard for .223 Rem/5.56x45mm AR-15 rifles. This means compatibility with the vast majority of brakes, flash hiders, and suppressors on the market. Always confirm your muzzle device's threading before purchase.
Yes. This lower parts kit contains the components that install into a lower receiver; it does not include the lower itself. You will need to source a separate AR-15 lower receiver to complete your build.
SKU: 115669232 • Width: 5.5in • Height: 5.4in • Depth: 16.1in • Weight: 6.1oz