Quick update - had the rifle back out to the range today. Same 200gr bullets and same powder and charge, but this time added kapok fiber as a filler. Velocity increased 120fps to 2085fps and std dev decreased from 121 to 18fps for a 10 shot group. So much more consistent. Results on paper were a little bit confusing. Not awful but not really better than load w/o filler. Need to digest what I was getting. Will post pics later.