Thread: Case head separation imminent

Originally Posted by Padox

As per instructions on dies

Greetings @Padox,
Congratulations you have identified the problem. My son lent me some Hornady headspace comparators and some sets of the Redding competition shell holders earlier this year. I had long been in favour of neck sizing but he had been using the above kit for his target rifles. An extensive measuring session followed. This was a revelation. Only one of my rifles had a chamber that gave the desired 0.05 mm (0.002") shoulder bump when sized with the standard shell holder. With others the bump ranged from 0.1mm (0.006") to an outlier of 0.3mm (0.012'). The comparator clamps onto the jaws of your calliper which I assume you have and are not over expensive and before and after sizing measurements will tell you how much you are setting the shoulders back when sizing. You can then either purchase the shell holder kit (which are more expensive) or adjust your die by trial and error to get the desired shoulder bump. Once done your head separations will cease.
Regards and all the best Grandpamac.