Primer flashhole irregularity

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Shane Tuttle

Staff
O.K. bear with me:
I happened to look down inside of my new Federal .40 S&W brass. I see what looks like the primer flash hole is "peeled back". Kinda looks like they "punch" the hole, leaving the leftover metal, well, peeled back. Looks like rose petals.
My question is:
Is it best to leave that, or do I deburr it?
I've deburred those in the past on other cartridges, believing that it interferes with uniform ignition of the powder.
Anybody have some input on this matter?
 
T

Trapper L

New member
That's how the flash hole gets installed- they punch it thru. Lyman makes a flash hole deburring tool that costs under $10.00. It's a no brainer to use and will straighten up the burrs pretty quick. For most handloading, the flash holes aren't a big issue. If you are having accuracy issues or looking for better accuracy, flash holes CAN make a difference. Sometimes it's worth the work and sometimes there isn't any difference.
 
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from the Hip

New member
I do trim the flash hole on my .308 win cases. It will help with consistency. I do not bother with pistol cases or some of my other rifles case that I am not fussy about. I use a modified #2 ctr drill. I believe the Lyman tool is a #2 center drill that can be purchased from any industrial supply for $5-$10. If you were to deburr the inside well and barley kiss the primer side you would end up with an hour glass cross section with both angles being 30deg per side. I hope this helps.
 
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Shane Tuttle

Staff
From the Hip,
You bet it does.
Do you mean a #2 drill bit? I have access at work for those if that's what you mean. But, they have a 140 degree angle. Any different?
 
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flutedchamber

New member
The #2 center drill is not the same as a #2 drill. A center drill is shorter and usually double ended with a 60 degree included angle (30 degrees each side).
 
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