Sounds like improper adjustment if the neck wont hold the bullet. Make sure you read the right directions when you adjusted it. the neck sizer and the full length sizer adjust differently.
It may have been that, but I just reread the instructions and did it all over again. I think what I was doing wrong was once the primer was knocked out and it bottomed out against the shellholder. I wasn't putting any additional pressure behind it because I was thinking that I would feel some resistance like I did with full length die. So I redid it and put the cartridge back through it that I tried yesterday and once it bottomed out I put some additional pressure, it seems to have sized it(the neck).