Blackheart Crossbow String 39 1/2 In. Mission Sub-1xr

The Blackheart Crossbow String 39 1/2 In. Mission Sub-1xr is a precision replacement string engineered for hunters who demand reliability and consistent performance across multiple seasons. Whether you're preparing for early-season practice or mid-hunt string maintenance, this 39 1/2-inch string delivers the accuracy and durability that serious crossbow hunters expect. Built specifically for Mission Sub-1xr crossbows, this string replaces factory originals worn by repeated fire and weather exposure, restoring your bow to factory-spec performance.

BlackHeart strings are manufactured using a proven blend of advanced synthetic materials and time-honored bowstring construction techniques that balance longevity with minimal stretch. The GlideLock center serving is the standout feature—this proprietary design reduces friction between string and serving, dramatically decreases serving separation that can cause accuracy drift, and eliminates the ridge marks that typically develop between serving strands on conventional strings. This refined center serving geometry maintains consistent nocking point pressure shot after shot, a critical factor when precision matters in the field. At just 0.2 lbs, the string is lightweight enough to preserve bow speed without adding unnecessary mass to your rig.

Mission Sub-1xr owners benefit most from this replacement string after 300–500 shots, or whenever string condition shows visible fraying, inconsistent nocking feel, or creep. The 39 1/2-inch length ensures proper draw weight and brace height when installed per Mission specifications. Installation is straightforward for experienced hunters familiar with string replacement, though proper bow press setup is recommended to avoid timing issues. This string restores your crossbow's original ballistic potential, ensuring the same arrow velocity and grouping consistency you relied on when the bow was new.