Compressed Charge
A powder load that exceeds the free space inside the case, so the bullet physically compresses the propellant as it is seated to depth.
A compressed charge happens when the volume of powder is greater than the room left after the bullet reaches its final seating depth, forcing the base of the bullet to pack the granules down. This is common in slow-burning loads near maximum, where filling the case is the only way to reach target velocity. Reloaders often feel the resistance during seating and may hear a faint crunch as kernels settle.
Compression is not inherently dangerous, and many accurate magnum loads run lightly compressed, but it does demand attention because it can push bullets back out or crush powder over time. The degree of compression depends on the propellant’s density and the case’s capacity, so a charge that fills one brand of brass may overflow another. When a load runs heavily compressed, drop tubes, slower-metering powders, or a longer bullet seating can ease the fill.