I had a similar experience and was not getting brass hot enough. An engineer at a brass manufacturer told me to heat in a dark room til necks are orange and quench in water. The brass is then soft and consistent. I have tried many different methods and this seems to be the best way.This may just be a perceived problem but I've never seen this before. I had 50 rounds of Lapua brass with two firings and decided it was time to anneal with AMP Aztec. Everything went fine with the annealing process but when I full length resized, I noticed it was just a little more difficult than usual. I say a little bit because the die has always seemed to be very tight to me (Redding Type-S Full Length Bushing Die). Anyway, my die is set for .002 setback and the first few I did bumped the shoulder back .004-.005. I suppose this could be due to lack of spring-back after annealing? I adjusted the die for .002 and continued resizing. I noticed every case has a thin shiny ring around the case at the shoulder junction. I measured the area and it was the same as that of a resized case that had not yet been annealed. I other thing I noticed was that the shoulder junction is now very sharp where prior to annealing it was more rounded. If you drag your fingernail down the shoulder you can feel it slightly catch at the junction. Is this normal? Almost makes me wish I hadn't annealed!
View attachment 279924View attachment 279925
They didn't say and I didn't ask. Just sent a new die with a fired case sized by the old one and one by the new one.I just ran into this thread scrolling but I am curious as to what Redding said was wrong with the die. Or did they say nothing and just send you new die?