I'm kinda like Ragin'-cajn. I've loaded thousands of 44 Mag in the past, altho I no longer own one, and I never needed a filler. The only circumstance I can think of that you might need one in a 44 is if you're using a very light charge of a very fast burning powder, which is neither good nor necessary.
I use kapok as a filler in rifle cartridges where the powder charge is low in volume compared to the cartridge case. I do not use it in pistol at all. The lowest volume to case capacity powders I use in pistol are Bullseye and Clays which are similar in that they are consistant even in large cases. The only area where I know fillers are used in pistol is with Black powder in large cases where you want to reduce the charge and not allow a dangerous air space in the charge which BP requires. Fillers in pistol cartridges may be dangerous. I know that .40S&W loaded with 10mm bullets leaves too little or no air space and causes pressures to go off the chart and it is not recomended. When you ask about fillers in general you need to frame the question with a powder charge and powder type as well as the cartridge and bullet. That stool has four legs. JB
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