Ammo

The instructions that come with loading dies are understandably brief. After all, most handloaders are men and we men only read instructions as a last resort. If we do read them, they had better be short and to the point or we are prone to toss them aside with a suitable but obscene comment and just dive right in on our own. So the instructions that came with your set of dies are appropriate for the intended consumer and will get you started quite well. I suppose you could say the instructions that come with dies are the original "Quick Start" instructions that are common these days with a variety of products that men might get their hands on.

But for those who have mastered the basics and would like to learn the more advanced techniques of case sizing that will improve accuracy, lengthen case life, and all but eliminate the chances of case head separation, the following are step by step instructions for adjusting full length size dies for bottleneck rifle cartridges. The instructions begin, obviously enough, down where it says, "Step One", but bear with me a few paragraphs and I will explain why precise size die adjustment is important.

Most shooters are familiar with the term headspace but many do not fully understand what it means and why it is important to avoid excess headspace. Every cartridge has specifications as to correct headspace. With beltless bottleneck cartridges it's the distance from the boltface to the center of the shoulder. SAAMI sets the specifications for all commercial cartridges but it's not important that you know what these exact specifications are. It's only important that you size the case to fit your particular rifle.

Today's firearms and reloading dies are more precise than ever, but there are tolerances allowed. Firearms manufacturers allow some tolerance on the plus side of chamber specification for headspace and zero tolerance on the minus side. They do this to ensure all factory ammo will chamber in their rifle. Reloading die manufacturers do the opposite. Tolerances for their dies are on the minus side of the cartridge specifications because they want to ensure cartridges sized according to their directions will fit in any chamber designated for that cartridge. So if you happen to get a rifle chambered at the upper tolerance of the specification and a set of dies reamed at the low tolerance of the specification you can end up with a fair amount of headspace. Add to this the fact that all manufacturers sometimes goof and make a product outside their specified tolerances and you can see why it is a good idea to make sure your cases are sized precisely to fit your rifle and not just according to the die instructions.

So what happens if you do push the shoulder back too far in sizing a case and end up with excessive headspace? When the firing pin strikes the primer it will drive the cartridge forward in the chamber until the shoulder makes contact.