This article covers the most important aspects of cartridge brass preparation. Its also a continuation on my slow but steady series on
precision reloading. There are several things that can be done which affect
accuracy. Cartridge brass is yet another one of those. The information presented
here along with the information in my precsion reloading article should provide
a strong foundation for reloading some fairly accurate rifle ammunition. As I mentioned in my last precision reloading article, accuracy comes from a lot
of "little things" that when added together can make a difference. Therefore
attention to detail is of paramount importance in producing accurate handloads.
Again, all information here has the usual disclaimers on reloading safety.
Please follow all guidelines in reloading manuals regarding safe reloading
practices and powder charges. Any changes made to your reloading practices
require that you start with known safe powder charge and work up safe loads
Before I get started there are a couple basic precepts that need to be discussed. The first precept is consistency. This is a the most basic, yet important
aspect of reloading for accuracy. Consistency in case weights and length, powder
charges, lot numbers, bullet weight, etc. In regards to cartridge preparation, cases and bullets must must be relatively identical in weight and configuration, and they should be concentric with the center of gravity and match the boreline as close as
possible. A reloader can adapt many of the concepts I have presented, but
without being consistant, is doomed to fail and any chance of accuracy lost.
The second precept is the our responsibility as shooters. We need to ensure that
we have sound shooting techniques and can make a rifle perform to its full potential.
The most accurate rifle in the world will still only be as accurate as the individual shooting it . When I first started benchrest shooting and was at my first match I sat next to a wonderful , experienced benchrest shooter, Jim Stekl. Jim has certainly
shown that he has what it takes in the benchrest commmunity, as he is in the Benchrest Hall of Fame. Between relays I was talking to Jim , looking to take
advantage of his many years of experience. One thing that Jim said to me was simple, yet so very true. He said " You can get your reloading process down pat, and tune your ammo to your rifle so it can shoot one hole groups. However, in the
end it boils down to one thing, the nut behind the butt. " Which is my point here.
The last precept is an assumption that you , the shooter, has a desire or need to
produce accurate reloads. If you are satisfied with a 3 - 4" group at 100 yards then
no need to do any of these procedures. But, hopefully you have the desire and it will motivate you to buy the necessary additional tools for case preparation such as a neck turning tool, concentricity gauge and case length trimming tool.
Cases are not all created equal. Some manufacturers cases are very consistent in length, weight, and concentricity, some are not. Manufacturers
like Laupua and Federal's Match brass will produce a much higher yield of consistent brass then will several of the others.
The first aspect of actual case preparation is weight. The necks should be turned and flash holes deburred prior to weighing cases. Some shooters will not be able to neck turn, but if you do it needs to be done prior to weighing the cases. Digital scales are more commonly used now and much easier when weighing cases and bullets. I would separate cases that fall within 2 % of each other. When weighing cases you typically will find that some will weigh high and and some low, with the majority falling somewhere in the middle. You can certainly go for a lower percentage, however, I would wait till after you turn the necks, trim case length, and deburr the flash holes. This part of the process assumes you are working with new brass. If you are working with used brass then it would be best to tumble the brass, remove the primers and clean the primer pockets prior to weighing.
There are neck turning and case length trimming tools out there that do
a fine job . I personally use the Sinclair neck turning tool and case length trimming
fixture. Flash hole deburring tools are all pretty much the same.
I have heard that the K & M tools are also an excellent choice. The instructions
for usage are included with the tools and unless you get into custom chamberings
where chamber tolerances are "tight" as with cases like 6 PPC and 22 PPC,
then its usage is fairly straight forward. Your goal in turning the necks for most
hunting cartridges is to make the neck concentric. So I would take off only enough
brass to insure the neck is concentric and the neck thickness doesn't vary from
one side of the neck to the other. If there is variances in neck wall thickness then
when the bullet leaves the case there is a possiblilty that the bullet will "tip" or cant
just a little causing it to enter the rifling improperly . This will cause unneccessary
yaw on the bullet as it leaves the barrel resulting in an increased group size.
Trimming all cases after neck turning to the same length is need to be done because uneven case length would have a similiar result on accuracy for the same reasons as stated above. Please be sure to go by S.A.M.M.I. specifications listed in most reloading manuals when trimming case length. Be sure to chamfer the case mouth to remove burrs, after trimming the case lengths.
After trimming case length, deburring, and neck turning, go ahead and neck size the cases. Redding has a new series of dies out that are very good at neck sizing very accurately. The dies utilize neck sizing bushings that you purchase separately
that allow you to choose exactly how much you wish to size the necks. Typically,
the least amount of neck sizing that you need to do the better. The goal here is to size the neck just enough to hold the bullet firmly in the case. There are also other factors, for example, the type of magazine the cartridges are being used in, tubular verses a "clip" style magazine. The reason for neck sizing only as much as needed is because not only does it excessively work the brass to size back down to SAMMI
specifications but it also can have a tendency to affect case concentricity which
causes a resulting bullet alignment problem, affecting accuracy.
WORK IN PROGRESS, MORE TO FOLLOW