Originally Posted by noelf2
Compression is "required" to keep from losing fingers, eyes, and such.
It is generally, but not universally, agreed that cartridges (or muzzleloaders for that matter) loaded with black powder should have no air space between the powder and the projectile. It has been reported that high pressures can result from such an air space, resulting in damaged or destroyed firearms. For safety, do not leave any air space in your cartridges. Compression is NOT required for safe loading, just 100% loading density with no air space between powder and projectile.