Finally had a chance to put some lead in the ball mold from Track of the Wolf. See pictures below.
Although it probably makes some shootable lumps of lead, I'm not happy with the roundness of the balls or the performance of the mold, and don't recommend it if you expect a consistent ball. After trimming off the sprue, the balls average out to about 1.4 ounces each, which is a bit lighter than I would expect. These were cast from pure lead.
The diameter of the final balls varies from ~0.742" to ~0.746" when measured to either side of the mold "seam", but the seam itself expands the diameter out to 0.776" or so. See second photo. The advertised 0.76" diameter is therefore a creative average. They roll down the barrel of the sawed-off coach gun just fine, but won't enter the muzzle of the full-choked gun with 30" barrels (which is what I would have expected in any case).
The other problem is the absence of a "reservoir" funnel at the entrance to the mold (see bottom picture). As the lead cools it shrinks considerably, and the cone-shaped funnel at the lip of most molds is there to offer up spare melt to keep the mold full. I had to "top off" the mold as the lead cooled, several times, to avoid holes in the top of the ball. The funnel on a normal mold is formed into a moving steel plate that also serves to neatly shear off the sprue; in this case you have to do a bit of carving with a knife.
I'll try shooting one in the coach gun, but not with a full load of BP; even though it's shy of 1.6 oz, a 1.4 oz load seems to be on the heavy end.
Caveat emptor, and shoot safely.