Your issues are very similar issues one can get with spherical powders in rifle.
They like a full case and initial pressure. Cast and plastic dont offer the initial resistance that a metal clad bullet does and so irregular pressure curves develope that the shooter can hardly detect! A magnum primer may help.
Extruded, other than really slow ones is easier to light up.
A2400 or reloader1. H322, H4227 ( if you can find some).
Even blue dot should work used with caution.