REXUS UltraBolt 6.5 Grendel | 6mm ARC | 22 ARC AR15 Bolt

We have improved the AR15 6.5 Grendel/6mmARC/22ARC bolt by strengthening both the bolt body and extractor — all while working reliably within the constraints of standard AR15 barrel extensions — to be the best in the industry: We call it the UltraBolt.

Has a .136″ boltface counterbore depth, called Type 2 and which we call Mk136. Fits barrels chambered to headspace with a 0.136″ boltface depth. VERIFY your barrel’s headspace with your barrel manufacturer.

Our UltraBolt is a fully assembled AR15 bolt and is ready to drop in to your 6.5 Grendel, 22 ARC or 6mmARC build.

We love the 6.5 Grendel, 6mm ARC, 22 ARC family, and have poured our heart and soul into dedicated parts optimized for those superlative, multi-role cartridges in the AR15 platform.

The premier cartridges for AR15-style rifles — 6.5 Grendel and 6mm ARC and 22 ARC — need dedicated bolts specially designed for their case head, which is the same size as a 7.62×39 case head. Our UltraBolt is a fully assembled AR15 bolt, ready to drop in to your build. Bolt bodies are machined completely in one operation (which produces more consistent and accurate tolerances) from tough AISI 9310 VAR (Vacuum Arc Remelt) steel and finished with a tightly-controlled proprietary QPQ heat-treat process to accurately control cast depth and core hardness. Extractors are produced from mil-spec 4140 PH steel and are mil-spec shot-peened and manganese phosphate coated.

Mk136 (also called Type 2) boltface depth, which is 0.136″. Fits barrels chambered to headspace with a 0.136″ boltface depth. VERIFY your barrel’s headspace with your barrel manufacturer.