I have been playing off and on for a good while with .690 round balls in a 12 ga. with no usable results. I was looking around a antique store and found a box of molds. There was an old Ideal that pours a .307 RB with good handles. Most were the old Dixie Gun Works scissor type with no sprue plate. One happened to be .715 so I bought it and the Ideal.
The mold is crude and fussy to pour but it worked and was .715.
I have a Rem 870 smooth bore slug barrel with IC choke. The ball went through the choke with pressure from the heal of my hand. I loaded three with a BP brush wad and 20 grains of unique. I trimmed the shell to give a proper roll crimp. I shot them this morning, my target was a little shy of 25 yds. The group was 1 1/4 center to center in a perfect triangle. I think it's worth trying again, I have never got anything close to this.
I don't hunt much anymore but my place has thick cover, minute of a dear at 45-50 yds would be great.