I've seen articles about filler...even bought a small bag of buffer filler from Ballistics Products a couple years or so ago to experiment, haven't gotten around to it yet though
The article mentioned seating the op wad just a short way past the muzzle, then add the shot, then start adding the buffer and tapping the side of the barrel to get it to settle down into the shot...stopping when the buffer appears to have filled the shot charge,
Is that how you do it in your 16ga?
Do you carry pore-measured amounts of buffer or just a quantity of buffer and add some each time you reload until its the right amount?
Also, have you been able to quantify improvements in increased % of pattern density, and/or extended range of an effective pattern?