I have been mulling over a number of different ideas about boolit designs and I was wondering about how you might maximize usable case capacity for a given bullet weight in the context of a single-shot gun - well, you just move the mass outside the case. But there are a few details....
1) Determine the minimum amount of bullet that must be seated in the case to guarantee acceptable hold and coaxiality, then design for that seating depth.
2) Use as much of the throat as is practical, with as much of the bullet at bore diameter as possible.
3) If additional weight is desired, neck down the bullet and extend it into the bore.
In my CAD tinkering, this results in something that looks like of like a SWC with a long nose on it that doesn't taper much. Surely I'm not the first person to think along these lines, so there must be a reason I haven't seen bullets like this around. Does anybody know what goes wrong if you try something like this?
EDIT: See Post #6 for drawing of a boolit designed with these ideas in mind.