If there's too little powder in the case, then you can get erratic ignition. Most good bottleneck rifle loads are going to nearly fill the case. There are exceptions.
In pistol cartridges I like loads that make it impossible to double charge the cartridge without powder spilling over obviously.
Good response. Too little powder can
sometimes be more dangerous than too much powder. Most of my rifle type ammo is loaded with brass nearly full of powder. I have never found a compressed load that was more accurate or reaching speeds to make it more desirable than a load going up to base of the bullet.
Some of my pistol loads use just a little bit of powder. On these, I use a foam pad to keep the powder near the primer. Gives better ignition and seems to be more uniform. This also helps me to avoid the double charge.
With a case partly full, you can get quite a bit of difference in pressures and velocity by bringing the gun up to level to fire vs bring the gun from pointed up position then down to fire. In one case the powder is up against the primer. In the other, the powder is down by the bullet and the primer flash is reaching for it.
Load safe!
Steve
