Thanks again for all your suggestions. The problem is solved. I sent my gunsmith a text message and took the die to him (Sunday morning!). He called me about an hour later to let me know I can pick up the die. He tapped the inside of the case and then gently tapped the tap it out from the opposite side. What he suggested to pay attention to: clean cases well before resizing (extracted case neck was not as clean as it should have been), and don't be stingy on lube. Also - clean dies well after using, disassemble and use a solvent. Excess lube inside a die will dry and in combination with other factors cause a stuck case. I usually do this but it's worth doing again before resizing to be sure. It was likely a combination of all of the above. I have been reloading for 35 years and never had this happen before. Dies are for a 375 H&H Improved (40 degree shoulder) so it's not easy to find a replacement. This afternoon, I used Brasso to polish the inside of the die and then cleaned it well. I also cleaned my cases individually in a drill press, it is much faster for me than tumbling since I usually reload about 20-30 at a time.
