"Nominal" mean there are no tolerances and no guarantees.
In other words, I am not encouraging people to use the program to design bore riding rifle bullets. My bore riding option was originally intended for revolvers and lever actions where nose tolerances are not critical.
BTW, most CBA competitors who shoot bore riding bullets use a "bump" die to guarantee the nose diameter. The beauty of a bump die is that any bullet can be swaged to fit your barrel perfectly. If the bullet diameter is too small, the bump die will bump it up. If the bullet diameter is too large, the bump die will swage it down.
At one time the Hanned Line offered bump dies, but they seem to have closed their doors. Don Eagan used to offer tapered nose dies to fit tapered throats, but he passed away. I am not sure if there is anyone still selling bump dies or nose dies at this time ?
In the future, I may be offering a few nose dies that allow sizing bore riding noses, i.e., perhaps a 0.360" x 0.351", or a 0.312" x 0.301". I don't have any plans to offer bump dies yet, but wouldn't rule it out if the market is there. I would have to charge enough to make it worth my time and I'm not sure that people would be willing to pay.