The TacFire SS-RK556 Build Kit (brand part no. SSRK556LPK) is a Sports South-exclusive kit that bundles nearly everything needed to build a .223 Rem/5.56x45mm NATO AR-15, short of the stripped lower receiver itself. It includes a 16-inch M4-contour barrel with a nitride finish, a birdcage flash hider with crush washer, and a 15-inch M-LOK free-float handguard, all built around a stripped billet upper receiver machined with M4 feed ramps. Rounding out the kit is a complete, USA-made lower parts kit with a Mil-Spec aluminum charging handle, dust cover, forward assist, standard end plate, castle nut, aluminum buffer tube, 3 oz buffer with spring, and an A2-style black pistol grip.

Key Specifications

• Includes a 16-inch M4-contour barrel with a nitride finish.
• Ships with a birdcage flash hider and crush washer.
• Includes a 15-inch M-LOK free-float handguard.
• Built around a stripped billet upper receiver with M4 feed ramps.
• Chambered for .223 Rem/5.56x45mm NATO, threaded 1/2×28.
• Includes a Mil-Spec aluminum charging handle with steel latch, dust cover, and forward assist.
• Includes a complete USA-made lower parts kit with an A2-style black pistol grip.
• Includes an aluminum buffer tube with a 3 oz buffer and spring.
• Sold as a Sports South-exclusive build kit.

Frequently Asked Questions

Does this kit include a lower receiver? No, this is a build kit covering the barrel, upper, handguard, and complete lower parts kit; the stripped or complete lower receiver is not included.

What caliber is this kit chambered for? .223 Remington/5.56x45mm NATO.

What handguard length is included? A 15-inch M-LOK free-float handguard.

Buy the TacFire 5.56 NATO AR-15 Build Kit

Get nearly everything you need for a 5.56 AR-15 build in one kit. Order the TacFire SS-RK556 Build Kit from TacFire in our AR15 build kits selection, shipped fast from our Lubbock, Texas gun shop.