Loading lower may make the flame larger instead of smaller. Less powder reaches a lower peak pressure, a lower peak pressure (generally) results in less powder burn, more unburnt powder results in a bigger fireball.
What you need to eliminate the fireball is a faster powder for a shorter barrel. My QuickLoad isn't handy at the moment but I can run some numbers later and see what it says.
__________________
Nobody plans to screw up their lives...
...they just don't plan not to.
-Andy Stanley
|