Enlarging the flash hole...
- Thread starter Robar
- Start date
The only reason I know for enlarging a flash hole would be to make them all uniform, in which case they would be enlarged by the smallest amount that would do that. Lapua brass for PPCs, BRs, .223, etc. all have a .060" or .065" flash hole which is one of the things that contributes to BR accuracy and consistency. American brass has a .080" or .085" flash hole.
There have been lots of "tests" done to determine the benefits of flash hole size, most not very conclusive. In my own test, using .223 Lapua brass, after I enlarged the flash holes to .085" all my load data changed and I won't do it again. By adjusting loads and changing primers I was able to get comparable accuracy.
In my non-technical opinion, the small hole focuses the flame of the primer deeper into the powder and causes more consistent ignition.
Sinclair, K&M, RCBS and others make tools to do the enlarging or uniforming.
There have been lots of "tests" done to determine the benefits of flash hole size, most not very conclusive. In my own test, using .223 Lapua brass, after I enlarged the flash holes to .085" all my load data changed and I won't do it again. By adjusting loads and changing primers I was able to get comparable accuracy.
In my non-technical opinion, the small hole focuses the flame of the primer deeper into the powder and causes more consistent ignition.
Sinclair, K&M, RCBS and others make tools to do the enlarging or uniforming.
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