Knight’s Armament SR-25 K6 16" 6.5 Creedmoor Upper Receiver Kit

Civilian version of the M110-K6 Upper

The Knight’s Armament SR-25 K6 is the commercial counterpart to the M110K6, purpose-built to put rapid precision fire and 6.5 Creedmoor external ballistics into a compact 16-inch SR-25. KAC pairs a 5R cut-rifled 416R stainless barrel, fast 1:7.5 twist, dimpled hybrid-medium profile, URX6 handguard, high-pressure dual-ejector bolt and QDC-compatible muzzle system into a purpose-built compact precision upper.

The result is more than a shortened precision rifle. Current K6 literature describes ballistic performance exceeding that of a 20-inch 7.62mm rifle, while producing a weapon that is easier to carry, faster to employ and far more manageable once a suppressor and modern observation equipment are added.

• 16" 6.5 Creedmoor Barrel — Compact enough for a suppressed field rifle while preserving the long-range advantages of 6.5 Creedmoor.
• 5R Cut-Rifled 416R Stainless Barrel — Premium precision-barrel construction with KAC’s distinctive dimpled hybrid-medium contour.
• 1:7.5 Twist — Faster than the 1:8 twist used on KAC’s earlier 22-inch 6.5 Creedmoor PR upper.
• High-Pressure Dual-Ejector Bolt — Improves suppressed and unsuppressed function in adverse conditions while extending service life.
• URX6 M-LOK Handguard — Resists impact-induced shift and provides seven sides of M-LOK with a continuous top MIL-STD-1913 rail.
• QDC-Compatible 7.62 Brake — Reduces recoil while providing the interface for applicable Knight’s 7.62 QDC signature-reduction devices.
• Factory KAC System — Barrel, bolt, receiver, rail and muzzle components are engineered together rather than assembled from substitutes.

The SR-25 Evolves Again

The SR-25 is unusual because its commercial and military development have remained closely connected. Eugene Stoner’s large-frame work began with the AR-10; decades later, working with C. Reed Knight, he returned to that architecture in what became the SR-25. Military use evolved through the Mk 11 Mod 0 and then the M110 Semi-Automatic Sniper System. Today KAC describes the current SR-25 Mod 2.6 commercial family as mirroring its M110 line.

That relationship is unusually direct with the K6. KAC’s M110K6 uses the same defining barrel formula as this commercial upper: 16 inches, 6.5 Creedmoor, 1:7.5 twist, 5R cut rifling, 416R stainless steel and a dimpled hybrid-medium profile. This is not a clone of an M110K6 assembled from similar parts; it is the commercial expression of the same current KAC engineering family.

Not a Shortened 22-Inch PR Upper

KAC’s earlier 6.5 Creedmoor PR Mod 2 followed the traditional long-range formula: a 22-inch barrel, 1:8 twist and URX4 architecture. The K6 changes more than barrel length.

The faster twist, revised barrel profile, URX6 handguard and current muzzle architecture make the K6 its own configuration. That difference becomes especially useful once a precision gas gun carries a substantial optic, bipod, clip-on night vision or thermal device, range-finding equipment and a suppressor. At that point overall length, balance and maneuverability matter alongside muzzle velocity.

Why 6.5 Creedmoor at 16 Inches

The K6 also reflects a change in how a precision semiautomatic rifle is used. A 20- or 22-inch barrel makes sense when velocity is the overriding priority. A working rifle must balance that advantage against the length added by a suppressor, the weight of a serious optic, and increasingly the need to carry clip-on night vision, thermal or ranging equipment.

The K6 gives up barrel length deliberately so the complete system remains useful when all of those pieces are actually installed.

The URX6 is part of that system-level thinking. KAC emphasizes its resistance to impact-induced shift. Its free-float construction keeps accessory loads off the precision barrel, while the continuous 12-o’clock MIL-STD-1913 rail and seven-sided M-LOK layout provide extensive mounting space without returning to the bulk of a full quad rail.

The Barrel Gets Attention. The Bolt Deserves It.

The dimpled stainless barrel is the visible premium feature, but the high-pressure dual-ejector bolt is just as important to understanding the K6. Two ejectors are immediately apparent on the bolt face; the engineering behind them is intended to improve ejection reliability across suppressed and unsuppressed use, adverse conditions and extended service.

That helps explain the premium. The buyer is not paying simply for a Knight’s logo or a distinctive barrel. The value is concentrated in the components doing the difficult work: the cut-rifled barrel, bolt, receiver geometry, free-float rail and suppressor interface, engineered as one factory SR-25 system.

For the KAC enthusiast, that is what makes the K6 compelling. It compresses the Stoner/SR-25 lineage, modern 6.5 Creedmoor ballistics and current M110-family engineering into one compact upper.

Technical Specifications