Avoid reducing loads below the recommended "start" load. The real danger lies in when the amount of propellant is so low that when the cartridge is laid horizontal (in the shooting position), there are two separated amounts of propellant within the case. This, as if one amount of propellant is laying up near the bullet, while the second amount of powder is back near the primer. These two amounts of propellant will then be separated, with only air between. When the propellant nearest the primer is ignited, this ignition must JUMP to the front amount of propellant, up near the bullet. This jump causes greatly increased pressure within the case and has been known to cause catastrophic failure in some actions.