Your assumptions are correct. A proper crimp holds the bullet a little longer, allowing the pressure to build up a little more before the bullet starts it's journey. Various test data I have seen also indicates that ignition is more consistent from one round to the next, which contributes to better grouping.
Collect a few different factory rounds (or borrow from friends) and inspect the crimps with an eye lupe. They'll all be a little different, but seeing for yourself is worth a thousand words.
|