Some of the stop rings are tapered to match the leade.
A friend over on ASSRA sent me a couple of bullets to draw. It's a 308281 but, a special made one. Note that the tapered band goes from .314 to .320 and that extra long base band. The one thing that I couldn't draw is the scraper groove, in front of the tapered band. There is no option for it in the program.
Most German stop ring bullets have cylindrical bands but, the chamber is cut long to except it and those bands can be full OD neck diameter.
The case runs about 1.811 - 1.83 but, the neck area of the chamber, can be +/- 1.938, so the stop ring can be as long as ~.13.
Frank