Many handloaders spend a lot of time on metallic case “preparation,” hoping to make them uniform. The theory is that cases as close as possible to exactly alike result in more consistent accuracy. In general this is true, but exactly how much case preparation it takes to make a difference varies. And exactly which changes make the biggest difference?

I’ve run tests on various case-prep techniques, finding that for the average big game rifle most are a waste of time, and even in a super-accurate varmint rifle much case-prep doesn’t make any noticeable difference. But some prepping definitely does help in any rifle, particularly work on the case neck.

There’s a reason for this. The neck is the “steering end” of the case, which helps start the bullet down the bore. If the neck is crooked, or its walls lop-sided, then the bullet begins its journey pointed slightly sideways. This definitely has an effect on accuracy.

There are ways to compensate for a crooked or lop-sided neck, such as custom seating dies that hold the bullet straighter during seating, or the Bersin tool that straightens crooked-seated bullets. But neither truly makes up for the bad neck. It’s far better to make sure the neck is straight and even-walled beforehand. Then even ordinary seating dies tend to seat bullets straightly.

The most common method of fixing case walls is to “turn” the necks with a tool on your case trimmer. Usually this involves a mandrel slightly smaller than the inside of the neck, along with a cutting tool that circles the outside of the neck, removing a thin sliver of brass.

Neck-turning can help, but not in the way most handloaders believe. When the neck is lop-sided the case body generally varies in thickness as well. When the powder ignites, the case expands more on one side than the other, pulling the front of the case out of alignment with the bore—so neck-turning lop-sided necks doesn’t help all that much.

As a result, generally I sort cases for even neck-thickness. An even neck right from the factory indicates the body of the case is also even. In varmint brass I look for not more than .001” in variance, and in most big game rounds .0015”. Most commercial American brass will have 90 to 95% of the cases inside those tolerances, and some European brass (such as Norma and, especially, Lapua) will all be within those numbers. The rejected brass can be used for offhand practice, dummy rounds, etc.