If the .760 ball is projecting out of the brass case any amount the star crimp likely would not work anyway. However, some time ago I bought from Harbor Freight this item,
https://www.harborfreight.com/shower-valve-socket-wrench-set-96322.html because one end of one of the sockets would fit some die rings that I did not have a wrench for at the time. I noticed today that the 27/32" end of one of the sockets will slide over the 10 gauge brass and put a six sided (not star crimp) taper crimp on the brass case. Nothing severe but just enough MAYBE to hold the projectile. If this turns out not to be the case when I get my order of round balls or begin to cast them, I will have to patch the round balls as has been suggested. C & H tool and die will not have these taper crimp dies any time soon.
Horace