Well, the short of it was I was successful in obtaining my goal. Not 100% happy with my load, but our group of 3 were able to harvest a bear (rifle), and we shot 3 grouse with my 12g loads.
I was not able to find any reliable source of load data with smokeless powder. Emailed ADI in Australia (makers of many powders) and I received a form letter saying they can't give me a load. Emailed Hodgedon - no reply. Found a load on the internet that I was NOT willing to try, although based on my reloading experience I could believe it would work. Had a guy from my local gun club make me some subsonic loads, right near 1000 fps if I recall. They were, to me, too loud.
So, end result was I loaded up black powder (Pyrodex RS) loads. I used Lee scoops (I have the red and yellow sets). 2.11cc of Pyrodex and 3.1cc of #7.5 lead shot. Took a Challenger trap hull (blue), cut it down, Cheddite 209 primer, 2.11cc Pyrodex RS (red dipper), cardboard disc, 3.1cc lead shot (yellow dipper), cardboard disc, then white glue around the upper disc to seal it.
With the first grouse, first shot knocked the grouse down, then my buddy fired a second shot (double barreled shotgun) at it to finish it. We then decided to "double blast" future grouse aka pull both triggers. If the grouse were close enough and sitting/standing no problems. Tried a couple of single shots at flushed birds without success (we're not accurate? not enough shot? too weak? or some combo...) In any case, the loads, even double blasted, were sufficiently quiet that we had no concerns about scaring any bears or other wildlife.
I suspect that instead of using #7.5 shot I will try larger shot for next fall. Or maybe make a duplex load and put in some steel BBs (from my BB gun) with the shot. My big concern was noise, and I probably should have experimented by shooting targets other than paper or aluminum pop cans. But at the end of the 3 day hunt, 1 bear and 3 grouse.
Thanks for asking!
