Using Once-Fired Military Brass
by Stuart A. Leach a.k.a. "the Colorado Gray Fox"
Every NRA Highpower shooter is tempted to use the once-fired 30-06, 7.62/308 and 5.56/223 military brass advertised in magazines and catalogs. The price is usually low compared with virgin commercial cases, and it somehow seems right to use GI brass in a service rifle. There are a few things to know about military brass before you start using it for competition, and I'd like to offer a few hints and tips.
Military brass is available from various sources, and in various conditions. Dealers actually package by weight, so the box or bag may be a few rounds short or long. Cheapest will be standard NATO ball cases, straight from the training ranges. It will be dirty, some cases will be damaged, and may be from mixed lots or several makers. It may have been fired in rifles or machine guns. As price goes up, so does quality- cleaner, sorted by headstamp, etc. The highest grade is once fired GI match brass, which will have been fired in rifles, and has no primer crimp. GI 7.62/308 match is getting scarce as military competitors switch to the M16.
Keep in mind that military 7.62/308 and 30-06 brass contains more metal than commercial cases. GI 30 caliber cases weigh 7 to 10% more than civilian brass; the extra metal is found in the rear third of the case. This means less internal volume, and powder charges need to be reduced to avoid excessive pressure. There is little difference between military and commercial 223Rem/5.56NATO brass.
Some dealers sell brass that has been "processed"- tumble cleaned, de-primed, and the primer retaining crimp removed. While this saves some work, I have seen a batch of 5.56/223 where the primer pocket was reamed too deeply, leaving the new primer unsupported for half its depth. Better to do the work yourself.
Assuming we have a batch of NATO ball cases, here are the steps to get it ready for use:
Inspect the cases, and throw out any with serious damage to mouth or rim. True up out-of-round case mouths with a tapered punch, such as a nail set, so they will enter the sizing die smoothly.
De-prime with a Lee or RCBS de-prime die. Then clean well in tumbler or vibratory cleaner for several hours. All the dirt and grit must be removed to avoid damage to sizing dies.
If the cases were fired in a loose chambered rifle, or a machine gun, a regular sizing die may not reduce the base diameter enough to chamber in your rifle. The thicker web and case walls spring back more than civilian cases. We usually don't know what sort of gun or guns the brass came from, so it's best to return each case to minimum dimensions before loading and firing the first time in your rifle. Lube the cases well, inside and out, and size in a special small base die. I share small base dies with other shooters. Clean again to remove sizing lube. Trim to length, then chamfer and deburr case mouths.
Ream or swage out the primer crimp. Reaming cuts away the crimp, using an inexpensive hand tool. Reaming carelessly can result in an oversize or oval pocket. Swaging moves metal out of the way, and slightly work hardens the pocket area. Swaging tools (RCBS is adequate, Dillon is superb) are more costly and complex, but once adjusted do a better job than reaming. Use a case mouth chamfer tool to put a light chamfer on the pocket to ease entry of the new primer.
For best results, use a flash hole reamer to remove
internal burrs. A primer pocket uniformer will also
help insure consistent ignition by making the
pockets of equal depth, and flat on the bottom.