Here's a cartoon to help explain....
CZ intended for you to be shooting a bullet ogive shape like the example in the center. The RN misses the lands of the rifling AND misses touching the freebore.
You said you are using a "truncated" ogive, and by that I guess you mean a
truncated cone, like an XTP. These are problematic becasue the full dia protrudes out of the case. The full diameter then might collide with the beginning of the rifling, as in the left hand example.
AND with a
lead bullet will probably "hug" the freebore as well, which is why I advised you to get the bullet's diameter down to 0.355". Only then you will you be able to differentiate between freebore "hugging" (not so bad), and colliding with the rifling (
very bad).
Additionally, becasue the 9mm incorporates a tapered cartridge fitting into a tapered bore, the diameter of the taper crimp becomes one of the items that is
extraordinarily important. That's "
extraordinarily important" as in
mission critical, must-have information, do not pass GO, do not go any further until you verify that the taper crimp is indeed 0.379" or smaller. This becasue sloppy taper crimp work mimics the bullet hitting the rifling and you cannot see inside the chamber to tell which it is. Therefore the only way to go forward is to rule it out by knowing
exactly what the taper crimp diameter is.
So you need to stop right here and read this...
http://www.czfirearms.us/index.php?topic=78873.0Some parts of reloading are Art, and some are Science. This part is Science, so you
must have your numbers right or it's not going to work.
No guessing allowed. Hope this helps.