Question about the flash hole

[Bob with the 66]

Hello all,

It the flash hole a common size between shells?

Example: 7mm BR to a 30-06, to a 7mm Weatherby mag?

I planned on de-burring each of my 7mm BR brass with a hand tool that I picked up this weekend, but I figured I better ask if I need a specific size for this round. Or is it one size fits all?

Bob,

 

[MGYSGT]

The Lapua holes are smaller than most others.

 

[Laurie]

There are two nominal sizes - 1.5mm (0.059") and 2mm (0.080")

The smaller diameter is only used in:

.220 Russian match cases and those derived from it, ie PPCs and similar.
All BR family cases, ie 6BR and 7BR and others derived from them such as the Dasher.
6.5X47mm Lapua
.308 Win Lapua 'Palma' small-primer brass only. (All other current makes and grades of .308 use large primers and the larger size flash-hole)
Out of production but occasionally found, Remington UBBR brass - thin-walled .308 Win form cases designed for reforming into wildcats and smaller precision-shooting cases.

Everything else uses the large (0.080") flash-hole whether .22 Hornet or forty odd calibre elephant. Oh ... I presume .50BMG uses something larger still, but never had any cause to handload this number.

These are of course for Boxer primed cases (single flash-hole). Berdan are completely different.

Sinclair, K&M and one or two others sell two flash-hole uniforming tools to suit the two diameters.

Note these are nominal diameters. The small version is usually very accurately done especially by Lapua which drills them. Many of the standard 0.080" type come larger than that from the factory as they're punched. You'll find that a uniformer simply doesn't remove metal from the hole sides of some makes and lots of brass.

 

[Bob with the 66]

Thank you, Glad I asked.

 

[fguffey]

Bob with the 66, things have changed, I have a flash hole gage. There was a time when the size/diameter of the flash hole changed. The flash hole gage is helpful for those that measure before and again after, same with shell holders, there are shell holders that fit.

F. Guffey