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Swapping a standard AR-15 over to 450 Bushmaster comes down to two parts: the barrel and the bolt. This is the bolt half of that equation, machined specifically for the fat .450 case head so it locks up correctly against a 450 barrel extension. The face is bored out considerably wider than a 5.56 bolt, which is exactly what the big straight-wall cartridge needs to headspace and feed reliably. If you already have a 450 barrel or complete upper waiting on a bolt, this is the piece that finishes the job.
WMD Guns built its name on coatings, and NiB-X is their proprietary take on nickel boron. It lands around 40 percent harder than chrome with a naturally slick, low-friction surface that resists carbon buildup instead of collecting it. In plain terms, that means smoother locking and unlocking, easier extraction, and cleanup that often amounts to wiping the carbon off with a rag. The coating is electroless and bonds at the molecular level, so it holds up to serious round counts without flaking or wearing thin.
Because nickel boron is self-lubricating, you can run this bolt with a light film of oil rather than drowning it. Less lube means less grit and fouling sticking around, which is a real advantage on a hard-recoiling round like the 450 that puts extra stress on the extractor and locking lugs. The finish also adds a solid layer of corrosion resistance, handy for a deer rifle that sees damp mornings and long stretches in the safe between seasons.
This is a bolt assembly on its own, not a complete bolt carrier group, so it drops into your existing 450 Bushmaster carrier and works with a standard mil-spec AR-15 lower. It pairs naturally with a matching 450 barrel and modified magazine to complete the big-bore setup. Made in the USA to WMD's tight tolerances, it's a straightforward upgrade for anyone chasing reliable feeding and low-maintenance function out of a straight-wall AR.
This is the bolt assembly only, not a full bolt carrier group. It's meant to drop into your existing carrier when you're building or converting an upper to 450 Bushmaster. If you need the whole group, WMD also offers a complete NiB-X 450 Bushmaster BCG.
The 450 Bushmaster uses a much larger case head than 5.56, so the bolt face is bored out wider to fit that bigger rim. A standard 5.56 bolt physically won't chamber or headspace the 450 round. Swapping the barrel and bolt is what turns a standard AR-15 into a 450 Bushmaster.
NiB-X is WMD's proprietary nickel boron finish that runs around 40 percent harder than chrome and is naturally slick. That translates to smoother lockup and extraction, strong corrosion resistance, and cleanup that usually just means wiping the carbon off with a rag. On a hard-recoiling big-bore round, that low-friction, easy-clean surface earns its keep.
Yes, it's built to mil-spec tolerances and works with a standard AR-15 lower and carrier. Pair it with a proper 450 Bushmaster barrel and a modified magazine to complete the conversion. As with any build, it's smart to check headspace with your specific barrel before running live ammo.
| UPC | 854839008566 |
|---|---|
| Manufacturer | |
| Manufacturer Part Number | 1-NIBXBA450 |
| Color | Nickel |
| Product Type | Part |
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