Case sorting & selection

Excerpt from Sinclair's 10th Edition Reloading & Shooting Manual
by Fred Sinclair and Bill Gravatt

This article is an excerpt from Chapter 3 of the Sinclair International Precision Reloading & Shooting Handbook - 10th Edition. The chapter continues with an in depth discussion on preparing cases for accurate loads after the selection process.

The first thing you have to do is acquire some cases. Our personal prejudice and strong recommendation is to start with brand new, unfired cases, or at a minimum, fired cases from factory ammo that has been fired in the same rifle you are reloading for. We are talking about getting the most out of your rifle, and trying to save a few dollars on cheap or used cases is a waste of time and effort.

These words are coming from two guys whose pictures should be beside the word "tightwad" in the dictionary.

Brass that has been fired and reloaded several times becomes "work hardened" and brittle, and will not respond properly to some case preparation activities.

Military brass, even the match type, is of a harder alloy and is usually not manufactured with reloading in mind. Brass life is generally short with this type of brass, and the end result will be frequent replacement.

Remington, Winchester, Lapua, Norma, Sako, IMI, and Federal all offer new brass cases for the reloader. Some of it is available in boxes of 20 while other brass is available in bulk only.

Regardless of how much brass you buy, or where you buy it, insist on the same lot. We have heard from some reloaders who feel bulk brass is inferior to boxed brass, but we have checked with several manufacturers and they say all the brass comes off the same line. Some of it goes into drums of 2000 and some goes to a boxing line. Our rule of thumb is that if we want to end up with 100 good cases, we need to start with 125.

We know from past experience that 20% will usually be sorted out for one reason or another. A lot depends on the quality of the production run and how finite your sorting criteria is. Sometimes, unfortunately, the European brass is of better quality than American brass. Some of the European manufacturers machine the case heads, drill the flash holes and can usually produce cases with more consistent wall thickness and weight. You may reject more cases when using American brass (but not always).

Visual case inspection is the first preparation step after you have rounded up your cases. Look for creases or splits in the neck and shoulder area of the cases and throw these away. Dented cases can usually be straightened. In the photo, the first case from the left is only slightly dented and would be kept. The second and fourth cases are severely dented from shipping and would be culled. The third and fifth cases would be rejected for severe manufacturing defects.

With the popularity of electronic digital scales, weighing cases is becoming a more popular method of sorting. We feel that a variance of 1.5% of case weight or less is an acceptable level for keeping cases in a group. When we select cases for a competition rifle or a varmint rifle, we will weigh 100% of the cases in a batch. In every batch we weigh there are always a few cases that have extreme weight variations (plus or minus). The reason for using case weight as a difference is that body wall thickness may be different in cases of different weights which, in turn, can affect case capacity. Differing case wall thicknesses will cause cases to react differently when they are fired.

When shooting long range we will especially weigh every cartridge. We feel that at these distances the weight variance variable should be eliminated.

Flash hole gauging is an operation that some reloaders do, either for a percentage of their cases or for all of them. Most commercial cartridge manufacturers specify a 0.082" flash hole diameter. There are an increasing number of manufacturers using a 0.058" to 0.062" flash hole on some of the target cases such as the PPC, 6BR, and 223 Remington. If you are checking the .082" flash holes, use a #45 wire size drill bit as a gage. We don't worry about the undersized flash holes (.058" to .062"), since the flash hole deburring tool will make them uniform. Checking flash holes is probably a step that should be done more often due to the fact that consistent ignition is so important to accuracy reloading.

The next step in the case prep process is to check the case neck wall thickness. Variances in neck wall thickness are also an indication of body wall thickness. We need to see how the neck thickness of a particular case compares when measured around the circumference (we usually check 4 points, 90¼ apart), and how the average neck thickness of the cases varies in a particular lot.

Variances in neck wall thickness can lead to several performance problems. Extreme variations result in misalignment of the loaded round in the chamber. When rounds like this are fired, the chamber seals differently producing pressure and velocity differences. The bullets will not be centered in the rifle's bore if case thickness variance is extreme. Variations in neck tension can also be a result of this problem, especially when one is using bushing type dies.

Body wall thickness variances can lead to the cases laying differently in the chamber from shot to shot. It also can be an indication of variations in case capacity which creates slight differences in load density. All of this sounds a little far fetched, but the slightest difference between two loaded rounds can and will show up down range, especially at longer yardages. Depending on what activity we were loading for, we would be concerned about cases that differ in neck wall thickness by 0.0015" or more. We would also be concerned if an individual case had variances of 0.0015" when checked around its circumference. Either of these situations would indicate the need to neck turn your cases. We measure neck wall thickness with a Sinclair case neck micrometer or a ball micrometer and we measure for neck wall thickness variance with a Sinclair Neck wall thickness gage which uses a dial indicator to show variances.

For benchrest match shooting, we will sometimes throw out cases that differ in neck wall thickness too much, even though we will be turning the necks down to within a 0.0001" of each other. We cull these cases because of the high probability that case body wall thickness variances exist also.

Set concrete goals for what is acceptable and what is not. By all means, don't skip the visual inspection step even if you don't do anything else.