Kak K-Spec Ar Bolt 556/300Blk De Chr
$112.46
$124.95
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$12.49
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The Kak K-Spec AR bolt for 5.56 NATO and 300 Blackout is a complete, ready-to-run bolt assembly built around 9310 steel and hard chrome plating—designed for AR-15 builders and shooters who demand reliability without compromise. This is the heart of your upper receiver: a precision-machined bolt that handles both common intermediate cartridges and pairs seamlessly with any standard AR carrier. Whether you're assembling a duty rifle, a precision build, or a dedicated short-action upper, a quality bolt is non-negotiable, and the K-Spec delivers the durability and function you need to trust your gun.
What sets this bolt apart is its dual-ejector design, which improves case ejection consistency and reduces the risk of stovepipes or failures to eject—especially important if you're running suppressed, shooting heavy loads, or cycling through mixed ammunition at high volume. The 9310 steel undergoes magnetic particle inspection (MPI) to catch subsurface defects before they become malfunctions. Hard chrome plating protects against corrosion and wear, keeping the bolt smooth and reliable through thousands of rounds.
Note that this is a bolt-only component: it does not include the firing pin, cam pin, or firing pin retaining pin—those are typically sourced separately or as part of a dedicated carrier completion kit. If you're building a complete bolt carrier group, factor that into your parts list. The extractor is 4140 steel with phosphate coating, and both ejectors are precision-ground S7 tool steel, heat-treated for durability.
Key Features
- 9310 steel bolt with MPI testing for subsurface defect detection
- Hard chrome plated finish for corrosion resistance and longevity
- Dual ejectors for improved case ejection reliability
- 4140 steel extractor with phosphate coating
- S7 tool steel ejectors and cam pin—precision ground and heat treated
- Chambered for 5.56 NATO and 300 Blackout
- Compatible with any standard AR-15 carrier
Specifications
| Cartridge | 5.56 NATO, 300 Blackout |
| Bolt Material | 9310 steel, MPI tested, hard chrome plated |
| Extractor | 4140 steel, phosphate coated |
| Ejectors | S7 tool steel, ground and heat treated |
| Ejector Configuration | Dual ejectors |
| Platform | AR-15 |
| Not Included | Firing pin, cam pin, firing pin retaining pin |
Frequently Asked Questions
Does this bolt work with any AR-15 carrier?
Yes. The K-Spec bolt is designed to pair with any standard AR-15 carrier. It does not include its own carrier, so you'll need to source one separately or verify that your existing carrier is compatible with 5.56 NATO or 300 Blackout.
What do I need to complete a bolt carrier group?
This bolt does not include the firing pin, cam pin, or firing pin retaining pin. You'll need to source those separately—Kak Industry offers carrier completion kits for this purpose—and pair the bolt with a suitable carrier.
Is the chrome plating durable for high-round-count shooting?
The hard chrome plating is engineered for corrosion resistance and wear protection. Combined with the MPI-tested 9310 steel core and heat-treated ejector components, the bolt is built to withstand extended use. Proper maintenance and cleaning will maximize service life.
Can I use this bolt for 300 Blackout and 5.56 NATO interchangeably?
Yes, the K-Spec bolt is chambered for both 5.56 NATO and 300 Blackout, allowing you to use it in uppers configured for either cartridge.
