.310 Cadet (Martini) Data

.310 Cadet (Martini) Data

The .310 Cadet—also known as the .310 Greener or .310 Martini—is a vintage training cartridge developed around 1900 by W.W. Greener for the Martini Cadet rifle. It features a heeled bullet design and modest ballistics, making it ideal for cadet marksmanship and small-game shooting.

Typical factory loads launched a 120-grain (˜7.8 g) heeled lead bullet at approximately 1,200–1,350 fps (˜366–411 m/s), yielding energy levels similar to the .32-20 Winchester, though the bullet diameter is ~.323" (˜8.2 mm).

Modern handloaders adapt this cartridge using trimmed or modified .32-20 brass or custom cases, cast heeled bullets (.310–.323") or sourced custom jacketed bullets, and powders that produce safe pressures. Community data shows loads such as 5.3 gr of WST or 8.0 gr of ADI AR2205 producing velocities around 1,300–1,400 fps in factory-spec chambers.

Because the rifle’s single-shot Martini action and often older barrel date require caution, proper seating depth, neck tension, bullet diameter matching, and case preparation become critical. Leading and keyholing issues are frequently tied to undersized bullets or thin brass walls failing to obturate properly in the heeled design.

While the .310 Cadet won’t match modern high-velocity centerfire rifle cartridges, it remains accurate, mild-shooting, and historically significant. It’s a favorite among veterans and collectors of Australian and British cadet arms, as well as shooters who appreciate the nostalgic and technical challenge of reloading older training calibers.

Source: Wolfe Publishing.