Yes, it's been a long time since I started this thread, but I finally thought of asking Nosler whether the Solid Base Ballistic Tips I have are the early "blow up" version or the later improved version - and I used exactly that language.
They asked me for the lot number printed on the boxes so they could determine the year made.
The Ballistic Tip was introduced in 1984, and it turns out my red/green boxes of 100 were produced in 1993 and 1994.
The Nosler technician said that all of the major improvements to the BT - except for the continuous tweaking process all their bullets go through - were complete over that 9-10 year period.
He didn't explain how to interpret the lot number, but he told me how to find it: look on the bottom of the box for a set of numbers that start with 2 letters, then 2 numbers, followed by more letters and numbers.
For example, my 140gr 7mm bullets had a lot number of FS24c1. He said that indicated 1994.
Maybe someone else here can explain the code in detail, but I got all the information I needed from his response. I'm happy!
