Even if you just seat the bullet enough to hold it and do the final on the presses a squeezes in one would work better.
Have not seen the current hand models (my last lee loader was the pound in type that destroyed cases about circa 1973.
Or, get a generator and a Kerosene heater and warm the loading shop up!
Curtain off a small area maybe.
Various combination of ideas presented should be considered.
Getting powder out of zip lock bags with statics and lips is not a way to go.
Test tubes would be better but......