It's just my theory I am planning to verify soon: starling brass is longer, 0.750 vs 0.740-5. So when you make specific OAL, the seating depth in Starline is more, what means more pressure. All my loads with165 and 147 are just fine in all mixed headstamps with the exception of Starline.
Nope. It did not work. The theory was wrong. Starline brass is still sticky. I measured the diameter of the case near the case base where it's most expanded. Starline gives 0.391-2". The other headstamps - 0.388. It's clear that the brass used by Starline produces more expansion. Probably because of some metal specs. The only brass, which was absolutely not usable in 929 was turkish cartridges ZQ1. They gave 0.393 and were extremely difficult to extract even with a lot force, total lock-up.
The best cases for so far are Winchester and Federal in my 929.