.30-06 Spring. (7.62 x 63) Subsonic

The .30-06 Springfield (7.62×63mm) is a powerful, full-size rifle cartridge with a rich history in military and hunting applications. While it is not traditionally associated with subsonic shooting, it can be effectively loaded for subsonic performance with careful planning and attention to detail. Due to its large case capacity, similar to that of the 7.5×55 Swiss, a key challenge lies in safely igniting small powder charges without causing erratic performance or pressure fluctuations. Fast-burning powders such as Trail Boss, Vihtavuori N32C (Tin Star), or IMR Red are commonly used for their ability to create sufficient pressure and case fill while remaining within safe parameters.

For optimal subsonic performance, reloaders typically select heavy bullets—generally in the 200–240 grain range—such as the Sierra MatchKing 220gr or cast lead projectiles. These heavier bullets retain more energy at lower velocities and stabilize better in the slow-moving subsonic range (typically 1,050 fps or below). A 1:10 twist rate, standard in many .30-06 rifles, is generally adequate to stabilize these bullets. Subsonic .30-06 loads are best suited for bolt-action rifles, as achieving reliable cycling in semi-autos is difficult without suppressor-enhanced backpressure and tuned gas systems.

Special caution is needed to prevent squib loads due to undercharging, and all subsonic loads should be tested with a chronograph. When properly loaded and used with a suppressor, subsonic .30-06 can be exceptionally quiet and accurate, ideal for discreet shooting or training scenarios where noise reduction is a priority. Despite being unconventional, it offers impressive subsonic performance with the right bullet and setup.