doublegunner
Fantastic! That is just what I need for my #3. Will you please provide dimensions for the insert?
In this pic you can see I put Dichem on a cross sectioned 45/70 case, marked off the outside in 0.1" increments, and then measured the case thickness at the marks. With a spread sheet I then calculated for each these points, [the outside diameter of the case] minus [the thickness of the case] = filler diameter at that point.
I then put some 1/2" steel or Aluminum round stock in the lathe and using DRO on carriage and on the crossfeed, I did the taper in 0.1" steps.
Decapping the filled case takes planning. The flash hole must be drilled through the case filler with a diameter that has clearance for what you plan on using to decap the fired cases. I would suggest two airplane drills, one slightly larger.
The longer the barrel the more powder can be used and stay quiet.
The bullet must jam into the lands for a gas seal. Any gas that gets by slows down the bullet and increases the noise.
The action was closed and that forced the bullet into the lands.
0.6 gr Bullseye .....287 fps........ quiet
0.7 gr Bullseye .....384 fps........ quiet
0.8 gr Bullseye .....354 fps........ quiet
0.9 gr Bullseye .....388 fps........ hollow sound but quiet enough
1.0 gr Bullseye .....441 fps........ sounds like a loud pellet gun, but no blam
1.1 gr Bullseye .....418 fps........ sounds like a loud pellet gun, but no blam
1.2 gr Bullseye .....536 fps........ sounds like a very loud pellet gun, but no blam
1.0 gr Bullseye ..... shot with open sights at target at 27 yards, 2" low and 1/2" to the right.
I could hear the bullet hit the brush and dirt.
If the same shots were fired into a piece of plywood, this would be an extremely loud gun for the situation.