The compact barrel architecture developed around the SARC-6 line, offered on its own. The QMB-6 combines a 12.5-inch suppressor-ready envelope, 1:7 twist, and a choice of precision stainless or hard-use chrome-moly vanadium (CMV) steel—each barrel released only after gauge-based dimensional verification.
A compact 6mm ARC gives up velocity to a longer barrel; it does not surrender the cartridge's high-BC advantage. The published table supports a 12.5-inch expectation near 2,350–2,400 fps, roughly 86 percent of the 24-inch velocity and about 90 percent of the 20-inch reference. The projectile's aerodynamic efficiency—not a powder-burn myth—is what preserves useful reach.
Read the full analysis // FILE-004 in IntelligenceThe QMB-6 offers a precision 416R stainless option for shooters prioritizing machining consistency and a 4140 chrome-moly vanadium option for field-oriented use. Both are built around the same chamber, twist, crown, and suppressor-interface geometry, with Night Black and FDE finishes. They differ in profile: the button-rifled stainless barrel is a heavy profile with a .936-inch gas journal, which adds rigidity and reduces point-of-impact shift across a string (still not rated for sustained rapid fire); the CMV barrel is a standard profile with a .750-inch journal.
Same print // profile and steel selected by missionEvery barrel is verified for chamber and headspace, bore and groove consistency, crown geometry, gas interface, and muzzle-thread alignment before release. That is the same measurement-first discipline applied to every complete SARC-6, focused on the component that establishes the projectile's first conditions.
Dimensional release plan // gauge-verified before dispatch416R stainless or 4140 chrome-moly vanadium begins the same controlled print. The stainless blank is turned to a heavy profile with a .936-inch gas journal for rigidity, heat capacity, and less point-of-impact shift across a string; the CMV blank keeps the standard .750-inch journal for a lighter field barrel.
Button rifling and thermal stress relief around a 1:7 twist. The faster twist stabilizes the heaviest 6mm projectiles, from the 103–108 grain low-drag class on up, without giving anything away at the lighter end.
The 6mm ARC chamber is built around bore-axis control, gauge-verified headspace, and an extended feed-ramp extension for the cartridge's wider case-head geometry.
A recessed 11-degree crown and 5/8×24 suppressor-ready muzzle thread; thread alignment and crown geometry are part of final dimensional verification.
Carrier, destination, signature, and jurisdiction policies are confirmed at checkout before any order is accepted.
Direct where lawfulComponent coverage addresses defects in material and machining; throat erosion and normal wear are consumable-life conditions.
Written warranty controlsCompatibility, installation-documentation, ammunition-selection, and function questions connect directly to Quadradyn.
Qualified installation recommendedDimensions, compatibility, velocity, dispersion protocol, and inspection criteria accompany the production specification.
Data before claimsBarrel length & shipping notice. The QMB-6 is a non-serialized 12.5-inch barrel and ships direct only where lawful. Some states and localities restrict the purchase, possession, or shipment of barrels shorter than 16 inches, and installing a barrel under 16 inches on a rifle-configured firearm creates a short-barreled rifle regulated under the National Firearms Act, which requires federal approval before assembly. Quadradyn does not ship barrels to jurisdictions where they are prohibited. The purchaser is responsible for confirming that the barrel, and the firearm it will be installed on, are lawful under all federal, state, and local law before ordering.
