I make sure my powder is nice and damp. And I wipe my piston and puck die down between each press to try and eliminate crumbs ground between them during pressing.
One thing I can tell you - dry puck chunks (I have not felt spendy enough to sacrifice an entire puck) burn
vigorously. Almost as quick as regular corned powder.
Still makes me nervous pumping away with a grenade under the ram. One day I'm going to make my HF press electro-hydraulically operated with a pressure cut-off switch. Then the pressing operation can be remote.
Today I pressed out my first batch of willow-based powder. The pucks are now in the food dehydrator drying.
https://i.imgur.com/sABJv23l.jpg
Steve