It's darn hard to tell without being there but something maybe out of spec with either the dies or the brass. Since this is a new cartridge Hornady could have done something wrong or the brass may be thick in the neck or even too soft. I know a few people that have not been happy with different lots of Winchester brass in various calibers. Plus I have three sets of reloading dies from Hornady that work fine, BUT they are different to adjust than RCBS or Lee dies.