Base bleed

It expels gas into the low-pressure area behind the shell to reduce base drag (but does not produce thrust, unlike rocket-assisted projectiles).

Being percentage-based, the range extension is more useful on longer-range artillery where an increase of approximately 5–15 kilometres (3.1–9.3 mi) can be achieved, and it also was found that the reduced turbulence gave the projectiles a more consistent trajectory, resulting in tighter grouping, and efficient shelling more than 40 kilometres (25 mi) away.

Base bleed technology was developed in Sweden in the mid-1960s but took some time to spread and find its niche between cheaper classical ordnance and even more expensive rocket-assisted projectiles.

This means that, at a cost of only very little space to fit the gas generator in the casing, The principles were developed in Sweden in the mid-1960s by the Försvarets forskningsanstalt (abbreviated FOA) and the Artillery bureau at the Kungliga Materielförvaltningen (later the Försvarets Materielverk (FMV)) while working on a rocket-assisted projectile called "reatil".

Shortly thereafter the international rights were sold, eventually ending up with the Space Research Corporation (SRC), then owned by aeronautical engineer Gerald Bull.