6gr over weight with difficulty getting good fill-out in the mold both point to one thing---your lead has "too much" lead in it. Are you using pure lead, or are you running an alloy? Pure lead is going to cause not only pour/cast problems, but it's going to be too soft to run clean through your firearm.
Stick with the lower rating until you can evaluate what pressures are doing. Heavier bullets require less powder to achieve pressures A) due to more weight to accelerate causing higher resistance, and B) more bullet tends to mean less case volume due to slightly deeper seating depth to reach the same OAL. Less case volume builds higher pressure faster.
"Why is is called Common Sense when it seems so few actually possess it?"
Guns only have two enemies: Rust and Politicians.
Last edited by Rangefinder; December 19, 2010 at 01:39 AM.