December 26th, 2007

Inspect Your Flash Holes on New Brass

Quite a few novice reloaders have recently started visiting our site. One common question is “What should I watch out for when inspecting new brass?” First, always check the cases for obvious defects such as split necks, defective case heads, or dimpled shoulders. But don’t toss a case merely because the neck may be slightly out of round. We recommend you run an expander down the necks to straighten them out before loading, and reduce neck tension slightly. That will take care of minor neck dents.

If you’re using the brass for competition, you may want to weight-sort your cases. You can also benefit by sorting the brass using a Neck Wall Thickness Gauge. Even if your rifle has a “no-turn” neck chamber, you’ll get enhanced accuracy and more consistent velocities if you cull the brass with extremely non-uniform neck-wall thickness.

You’ll want to inspect the flash holes carefully. With domestic brass, you may find flash holes that are slightly off-center, or that are not consistent in diameter. Segregate the brass with off-center holes, and you can uniform the flash holes with a variety of tools. Normally Lapua and Norma brass have very consistent flash holes. However, in some recent lots, we’ve seen a little crescent-shaped sliver of brass around the edge of the flash hole (see photo). This can cause inconsistent ignition and should be removed. You can clean up the edge of the flash hole with a flash hole uniforming tool or a small bit fitted to a pin vise.

Note to newbies–Lapua 220 Russian and 6BR brass has a small flash hole, specified at 1.5mm, about .059″, in diameter. Select a tool that will clean up the flash hole without increasing the flash hole significantly. Some tools will ream the flash hole to .067″ or larger and that is too much. But the actual diameter of your flash holes (whether .059, .062, .067) after reaming is not that critical–so long as all your cases end up with the same hole diameter. Uniformity is the key. With many lots of Lapua brass we’ve found that flash hole reaming is not necessary for 95+ cases out of a box of 100. But you should inspect every case before you load.

Similar Posts: