Cal. 61
If you make a tapered bullet, the base is groove dia. less one or two thickness of paper, depends on how tight you want it. Up toward the nose ,just before the ogive, the dia. is the bore dia. less one or two thickness of paper, depending on how tight you want it. If the mold is a little to small you can polish it out a little with emery cloth till you get the right size. When the powder ignites, the bullet will be up-set filling the grooves. If you use too much powder it will up-set the whole bullet and all you will have is a slug of lead not really a bullet. It the bullet up-sets to much the gun will not be very accurate. :results:
The half reamers are used like a drill. You can only go straight in. I have a floating tool holder that I use when I use a half reamer. To make a mold you can step drill the cavity, then finish with the half reamer.
Olie :imo: