Flash hole uniforming

dcso3009

I have been trying various tricks with the primer pocket and flash hole and have a question...
Is there a problem with cutting on both sides of the flash hole? What I did was to cut a little from both the primer pocket and from inside the case. I tried it with a low power load in my 30-06 A-Bolt with great results.

FrancF

Perfect!
Thats the same as I do, Just kiss the flash hole on the primer end if its egg shaped a slite chamfer is all you need. a few Thou. goes a long way. IMHOP


NRA Life Endowment Member

JustC

are you referring to deburring the flash hole? if so this is a benchrest trick from way back. I do it to every lot of brass I prep.

why chase the game when the bullet can get em from here?....
Got Balistics?

FrancF

Justin- sounds like he is doing front and back- Its a great trick, old, but it works! as you said.


NRA Life Endowment Member

ContacFront

Cut front and back? Never seen or heard of that.

FrancF

OK-
In other words, he is cleaning up both ends of the flash hole. The powder side (Unless its premium brass) will have a burr. The primer side can be egg shaped, thus causing irregular ignition. So if you take the step to clean up the front an back side of the flash hole, the more uniform your ignition will be.

Most important! You do Not want to enlarge the flash hole, just make it round.

Think of it as just deburring a hole on both ends. Maybe someone out there has a graphic that will explain it better.



NRA Life Endowment Member

rimfire72

I do the inside of the case,but never thought about doing the primer side. I'll have to give that a try.

dcso3009

Thanks guys. The results were quite surprising. Like I said in a plinking load for my '06 it shaved almost 0.25" off the groups. Unfortunately my gun does not like light bullets and was shooting about 7/8". Now I will try it with my hunting loads, since that is what I use that rifle for.

FrancF

If anyone is confused about it, I will do a drawing on the subject.


NRA Life Endowment Member

Ray B

I hadn't trimmed the primer side of the hole; but did "deburr" the powder side. This helped some though I don't have any group measurement to quantify the improvement. I've read thta the best groups will be optained if the hole is centered, of the same diameter in opening and thickness, so if I'm going to get an accurate rifle, I probably should start working the cases over.

lcflcf

I have a question, I bought a deburring tool and do the inside but, But how do you do the primer side, My tool won't fit in the primer pocket, Thanks Les

FrancF

lcflcf


Thats beacuse you can't with the tool you are using. let me post a pic so you can see.


NRA Life Endowment Member

FrancF

The picture is crappy, But this the tool for deburring/chamfer the flash hole on the inside of the case. Then you use the same tool to give a slite-"just kiss it chamfer" Nothing more! to the flash hole on the primer side.


[img][/img]

Now Not to make this confusing, I also use a "Center Drill" To make the flash hole uniform. It is a little larger than the one shown.


NRA Life Endowment Member

lcflcf

Thanks FrancF, I got the picture now, Les