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Flash hole question

bigdumboy

Well-Known Member
Joined
Mar 23, 2011
Messages
295
Location
Shippensburg Pa
Is it a needed step in brass preparation or just a waste of time. What are the benefits of it? Will it help in a more uniform speed if you are shooting over a chronograph. Comments and opinion needed thank you.
 
Precision target shooters usually debur the flash hole. This helps with uniform ignition of the powder column. The holes are punched and as a result there is a bur around the inside of the hole. I haven't done a test to see what difference it makes. There is a tool made for this procedure so evidently someone thinks it helps.
 
Precision target shooters usually debur the flash hole. This helps with uniform ignition of the powder column. The holes are punched and as a result there is a bur around the inside of the hole. I haven't done a test to see what difference it makes. There is a tool made for this procedure so evidently someone thinks it helps.

Depends on the.brass you are using

I use Lapua and other than a visual check to make sure they are clear I leave.them alone.

I will say those tiny flash holes in 6br cases wreak havoc on my universal decapping.dies. real easy to bend the decapping pin.
 
Does it help? All depends on what you are trying to do. Are you trying to get 1" groups down to 1/2"? You probably won't see a difference. Trying to get 3/8" groups down to 1/4", maybe.

Test for yourself. De-burr the flash hole on 10 or 20 cases. Load these and load the same number that haven't been de-burred. Then do a blind bag test. Mark 2 bags or boxes, etc, 1 & 2 respectively. Have someone put the de-burred rounds in one bag/box and the other rounds in the remaining bag. This should be done in a manner that you don't know which is which. Take these to the range and shoot them as normal. After you have shot the rounds, you can find out which is which and compare the two groups for differences. The blind bag test keeps you from unconsiously influencing the outcome of the test. You won't be "trying harder" on the de-burred rounds as you won't know which is which.
 
IMO, unless you're obsessed with getting all shots into one hole (e.g. bench rest competition) it's a waste of time. (*)
I shoot long range competition. I know that, under a microscope, I can detect some irregularities in some of the flash holes. But if there's a difference in performance on target I've never seen anything significant enough for me to take the time to polish flash holes.
For the obsessed, I'd endorse the double blind test suggested earlier in this thread. For the rest of us; load 'em, shoot 'em, and enjoy yourself.

gun) - - - - - - (X)

(*)
If it's important enough to debure and polish flash holes, don't forget to:
Weigh each empty case for consistency
Check case capacity for consistency
Measure case neck thickness for consistency
Check runout to control maximums
Square up the neck with case trimmer
Weigh all bullets for consistency
Measure bullet lengths, base to ogive for consistency
Point all bullets for uniformity in shape
Monitor pressure during bullet seating
Check final runout for all seated bullets
Carry finished rounds in padded box to protect from impact during transport to the range
Then - enjoy yourself.
 
Cant hurt .
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Some brass does require deburring; just do not widen the hole diameter.
 
Never had to cut flash hole burr on Lapua, Nosler or Norma/WBY brass. I deburr others just for peace of mind, I'm retired so I have the time.
 
I shoot 1000yrd comp too, I de-burr most case brands like Rem, Win and Hornady or other US made brass. In fact, my lot of Winchester brass is just as accurate as my Lapua brass, once prepped.
The Lapua and Norma brass I use I don't touch the flash holes. I once had new Norma brass and due to not using it before, I decided to de-burr before looking into it further.
I felt quite some resistance to the drill entering the flash hole, didn't think much of it at the time. That brass shot terribly in testing, after talking with a fellow member at the club, he advised me to NOT touch ANY European made brass, it is DRILLED and is .078" flash hole, not .081" like US brass. The untouched brass is AWESOME in uniformity on case volume and the flash holes don't need cleaning up.
My Lapua brass is by far the best brass I have ever used, wish I had of kept more of it, didn't know at the time that Lapua would stop doing 300WM brass, the 300 I have will have to last, I guess. Haven't lost a single piece to a failure yet.

I feel the brand of brass is where it needs to be decided if the flash holes NEED to be prepped. I have some very clean flash holes on Winchester brass, and some that were not so clean.

Cheers.
gun)
 
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