How do you measure the neck to make sure you are not sizing it back too much?
I followed the instructions that came with my die set to a T, and the first case I tried, the neck actually buckled. I got it taken care of so it didn't buckle, but the next 2-3, the neck didn't seem to have a good angle to them. One of the guys on another forum I frequent suggested that I put a case in the press, raise it all the way, then screw the die in until I feel resistance. Pull the case back down, and turn the die another 1/8 to 1/4". I did this, and I think it may have solved my issue... it only pushed the neck back .002". I was very happy with that for the next 10 cases, but then I got one that the shoulder was really deformed on.. it may have had a 10 degree slope down to the neck. When I tried to resize that one, it pushed it back .002" like the rest, but the neck still looked the same.
This die set is the set I am using. The die in the middle is the one I am using, as stated by the instructions. The one on the left is probably the one I am supposed to be using, now that I look at it... but I had an issue with the decapper not removing the primer like it was supposed to.
Here is a picture of the instructions I have. I provided a link rather than resizing, just in case you need to zoom in on any particular section.
Instructions