Deburring flash holes???

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One thing I think is pretty funny. It is common for there to be dyed-in-the-wool flash hole deburrers even with no demonstrable benefit. Contrast that with the question of "do eccentric flash holes make any difference?" Ask the latter questions and the majority will confidently declare that eccentric flash holes make no difference even though they've never tested the hypothesis.

I have been saving cases with eccentric flash holes and maybe some day I'll do the test. In the mean time, I don't load them.
 
I use Lapua and Starline. I am sure Starline punches theirs, but I can not see nor get my finger in there to feel a burr.:)

I have seen some of the worst examples of the offenders, a hinged lid, a folded over fan, the volcano, and those should be attended to. I don't see how a raised burr on a nicely punched flash hole would hinder consistency, though. Further, I would speculate a short tube that directs the ignition to the center of the powder column may increase consistency in the burn. Rather than lighting it from the end. This could raise back pressure to the primer and possibly cause some other unbeknownst problem, let alone the difficulty in machining the tube.

Grumulkin said:
I have been saving cases with eccentric flash holes and maybe some day I'll do the test.
Click to expand...

Did you mean off center punched or the flash hole being oblong in shape?
I have six hundred Perfecta cases that were made in Italy, rather nice ones. And twenty of the worst Perfecta cases that I managed to get deprimed, the rest were too far off center to get. These later cases must have been made in a different factory, country, mindset.

Just musing over coffee...
What a nice day out.
 
Deburring flash holes should be gone about with the same caution of a cat eating a grindstone. Whacking off the burr is OK, but stop there. Serious problems have been caused by over-application of deburring tools resulting in a cone shaped flash tunnel. Without going into details, a nozzle effect is created that can, and has, result in unwanted (read dangerous) ignition excursions.
 
Offfhand said:
Without going into details,
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I would be terribly interested if you would... :)

Or if you could point the way to some reading I would be equally as grateful.

Grumulkin said:
Nice and round but off center.
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Then an experiment it is! It may be a while, but I will list it under "Deburring flash holes? An Experiment."

Now to find where I stashed the "to be lost" container of brass.;)

Edit: I suppose it should be "Non-Concentric Flash Holes? An Experiment."
 
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I'm 'quite certain' I'll never reach a level high enough to know the difference,,,,

Besides, what better excuse when you are out with your buddies and one 'misses the mark'???

"Dang! THAT'S the one I didn't de-burr!"
 
I am a twenty-year Vet every year I qualified as "Expert" with the M-16. But unlike some of you God never gave me the ability to stack one bullet on top of another. But he did give me the ability to teach and mentor my 7-year-old grandson. One of the things I have taught him is "anything worth doing is worth doing right".For you fellow old geezers I know that you all remember that saying but for you youngins that is the way we were taught.

Now, I have the Hornady Case Prep Center. After trimming I have 6 stations below to prep the brass. Station 1 I chamfer, station 2 I deburr Station 3 I have a brush to clean filings out of the case, station 4 I have a pocket reamer to remove military crimp, station 5 I have a primer pocket uniformer, That leave one station that is open. So on that sixth station, I use the Hornady flash hole deburring tool. Each piece of brass from start to finish take between 10 to 15 seconds. well worth the time.
 
I hope that I'm still around to teach my youngest grand daughter how to shoot a pistol.
My #3 born took to pistol after around two mags...then the light bulb turned on..
she understood sight-picture and start hitting the steel.
 
I de-burr and uniform the flash holes. Typically on rifle cases (not handguns) and as said, only once. I also check for length on new cases and regularly on fired cases. I've never decided if it improves accuracy or ignition, but it does allow one to detect serious 'odd' flash holes and correct the issue. Nor does it harm accuracy in the least.

I sort cases for weight, and only AFTER trimming to proper length and truing-deburring the flashhole. Makes me think I'm being careful.
 
https://www.thehighroad.org/index.p...stol-brass-primer-pocket.664288/#post-8229145

https://www.thehighroad.org/index.php?threads/flash-hole-deburring.764492/page-2#post-9664126

"Uniforming" (diameter) the flash hole is done by one part of the tool, and deburring the next step of the tool, assuming you have one that does both. without touching the outer brass. Deurring the flash hole should be like deburring a case mouth, just enough to knock off any burrs or hanging pieces from trimming, and just barely knocking off the 90 degree edge.

My old K&M tool that I used for 6PPC cases has a stop on it to keep one from cutting into the flash hole instead of just touching up the edge.

They look different today, but the concept is the same.

http://kmshooting.com/ppc-0-062-pro-flash-hole-uniformer.html

upppc062-1_780x662.jpg

When you are going through as much trouble as we did to form and prep 6 PPC from Lapua .22 Russian brass, doing the flash hole was a tiny part and so why not. Can I prove it helped? I sure can't. :)
 
Slamfire said:
I do believe that flash hole diameter makes a difference, but this was only determined by shooting a small batch of WW2 30-06 brass that had extra large primer holes. I don't know if I have the chronograph data anymore, or if I took it, but it is my recollection that there was a difference.
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I hear about people deburring the flash hole, but I don't think I have ever heard of anyone making sure the flash holes are all the same diameter. I've seen some substantial differences in pistol brass, but can't say that I have seen much difference in performance.

I think that any performance improvement by deburring flash holes would be "lost in the noise floor", to borrow a phrase from my trade. Still, I have a left over position on my case prep center, and it only takes a couple extra seconds, so why not. If it were a task that was a PITA, then I would not bother.

I would still like to see empirical data on this subject.
 
243winxb said:
This tool does the hole and removes the burr, like in the above photo.
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Oh, boy, another shiny reloading gadget I never knew I needed. :D

Ok, same question, does it make a difference? For me, probably not. I'm still trying to work on things I know make a difference.

It would be interesting, though, to try different size flash holes to determine the effect that has on consistency/accuracy.
 
Demi-human said:
Did one shoot better
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243 win brass , as it comes from the factory, averages about 3/4" .
After prep, weight sort, uniform flash hole, neck turn, shoulder bump in FL bushing die, sizing only 1/2 of the neck, average drops to under 1/2" @ 100 yards.

There are no more flyers that ruin a good group, after prep.

After reading about BR groups online in 2000, i had to try it at 300 yards. Took my 1976 Rem 40X woodchuck gun, with its shot out throat , to give it a try. I wish i had done all this when the rifles barrel was in better condition.

Put a 36X scope on it. Bought bushing die, neck turner , flash hole uniformer and Berger match bullets in 70 & 90 grs.

After load workup , went to 300 yards on a no wind/ no sun day. Fired 6 -5 shot groups. 3 groups were under 1" Good enough for me.

Is it worth all the trouble, probably not. Good time killer if retired.
 
Don't look now, but I think I see a burr on the flash hole that's been deburred in post # 32!

:D

(Great pics 243,, Thanks for sharing!)

I reckon somewhere along the line, some rather significant burrs have been observed, and if significant enough, that probably could end up with a slightly different burn than lesser burred cartridges.

If done right, there's certainly no harm done if it makes you feel like one less stone left unturned,,,
 
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Slamfire said:
A lot of the things we do, and accept as truth, we have never tested, but follow, because we think it works
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I think the reason is it takes a lot less time and effort to just do the "thing" than it would to test the "thing". Especially to test it correctly with a properly designed experiment and controls.
 
Some flash holes have big flaps hanging on them, no reason to leave them that way, just too easy and quick. But of course most folks who need it are buying better brass.
 
When I started shooting BR 6ppc we used Sako 220 Russian brass and the flash hole was .0590".

Click on the http://kmshooting.com/kmshooting/media/pdf/2.pdf you see Master uniformer and that's what we use.

Sinclair use to furnish small decapping pin for the ppc case. I'm not sure what the size it is today for the Lapua and Sinclair has something that open flash hole to .062". I have some Lapua 220 Russian in the cardboard box and it has .0590" flash hole.
 
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