Sierra 7.7mm 303 Cal 125gr SPT

Sierra 7.7mm 303 Cal 125gr SPT

The Sierra 7.7mm 303 Cal 125gr SPT is a precision component bullet engineered for handloaders pursuing controlled terminal performance and flat trajectories in classic .303 British and similar calibers. Featuring a .311‑inch diameter and a 125‑grain soft-point Spitzer profile, this bullet combines reliable expansion with smooth feeding—even in tubular-magazine and bolt-action rifles.

Boasting a tapered Spitzer ogive and thick copper-alloy jacket over a lead core, the 7.7mm 303 Cal 125gr SPT initiates predictable expansion upon impact, creating broad wound channels ideal for deer-sized game. The aerodynamic Spitzer shape also enhances velocity retention and reduces wind drift compared to round-nose counterparts.

Manufactured to tight component tolerances—125.0 grains weight, 0.311″ diameter, approximately 1.050″ overall length, and a sectional density near 0.205—the bullet features uniform jacket thickness, precise meplat alignment, and concentric construction. These qualities support repeatable seating depth, reliable pressures, and accurate grouping in matched rifles.

Optimized for twist rates between 1:9 and 1:12, this SPT bullet performs at velocities of 2,200–2,800 fps, delivering deep penetration with controlled expansion up to typical engagement ranges (~200 yds). Hunters report dependable terminal results with minimal fragmentation and consistent accuracy.

As a component bullet, the Sierra 7.7mm 303 Cal 125gr SPT empowers reloaders with full control over powder, primer selection, and seating depth—enabling tailored load development for recoil, trajectory, and terminal effect. It is not factory-loaded ammunition, but a precision soft-point Spitzer built for ethical hunting and consistent performance.