Flash Hole deburring?


November 24, 2006, 09:10 PM
Has anyone done formal testing to see if this actually helps accuracy? I have 150 rounds of the same lot winny 308 brass and shot 100 without doing this (mainly cuz I don't have the tool) and was going to buy the tool to see but might want to save the measly 10.00 I would spend on it.

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Mark whiz
November 24, 2006, 09:19 PM
I've gotten to the point that I debur the flash holes in all my brass before the first reload. I can't really say it has made any noticeable difference in my ammo's accuracy - but at least I know that I've taken that little chore out of the equation.
Consistency in preparation is the key to making consistent ammo and consistent flash holes sure can't hurt what you're doing.

.38 Special
November 24, 2006, 09:50 PM
The late Creighton Audette -- a famous name in the benchrest world -- was know for his controlled and exhaustive tests of such things. He "debunked" primer pocket uniforming entirely, using such testing. He also discovered that deburring factory flash holes could make a real difference, though it takes a better than average rifle to prove it. Your 1.5 MOA sporter probably won't show the difference, but your 0.5 MOA bull barrel job might. This is assuming, of course, punched flash holes. Drilled ones don't need any fixing.


November 25, 2006, 04:03 PM
It might make a difference in two ways. First, as 38 Special noted, if you have an already-accurate rifle it might improve your accuracy a tad. Improvement probably can be detected, but it will be marginal. When I shot high-power rifle matches (200/300/600 yards) the common advice was to save the heavy duty case prep, which included deburring flash holes, for the 600 yard (prone, slow fire) ammo, as the "short range" stages which were shot standing or rapid fire were much less affected by pure accuracy than by many other factors. (I have the impression that the national champion level shooters ignored this advice, and fully prepped all their ammo, as even one point dropped could make a huge difference to their standing.)

Second, and perhaps more important to us "ordinary" shooters, is the extra confidence that can come from knowing that you've made the most accurate ammo you can within the limits of your time and available tools, so that if you do your part the bullet is more likely to go where you aimed it.

So --- in the end it will depend on what your application and requirements are. For hunting deer at short range it probably wouldn't make a particle of difference. If you're hunting bullseyes at 600 yards with a rifle (AND personal shooting skills and technique) that can do it, then it probably would be worth the effort. As you know, the tool isn't expensive, it's self-limiting so you can chuck it in a cordless drill and fix cases while you watch TV (but be sure you have a way to catch the pile of brass dust you will generate), and you only have to do it to a case once.

November 25, 2006, 04:11 PM
Do your handloads match good factory loads for accuracy? If so I might not bother, if not I might try everything.

November 25, 2006, 04:16 PM
I do it. Just did 120 rounds of LC92 that I deburred from inside. If it MIGHT make a difference, why not do it? When I hit those big chips hanging inside the flash hole with my tool, I THINK I am making the brass more uniform.

I'm a NM State Team shooter. High Master with service rifle. Distinguished. Won a few regionals. Louisiana State Champ twice. I doubt if it is the flash holes but I don't want to have to wonder if it is.

The Bushmaster
November 25, 2006, 04:28 PM
For over 45 years of swinging wrenches and supervising wrench swingers. It has been a habit to remove burrs from any and all machinery and their respective parts. Removing burrs from rifle flash holes just seems natural and correct to me. Whether it helps...I haven't got the slightest idea, but out of habit (I don't know any better), I still do it. Besides it looks more professional...:D

November 25, 2006, 04:35 PM
If you are a serious brench rest shooter then deburr them otherwise don't waste your time.

November 25, 2006, 04:48 PM
There was an articule in Varmit Hunter Magazine, [I think] where a guy took 1000 fresh cases and divided them up into groups of 50. He tried all the tricks such as deburing the flash hole , neck turning, different crimps, lengths , ect. Shot them out of a new barell properly seasoned. only two things made a noticable difference. Flash hole de burring and a Lee factory crimp die. If the cases have the flash hole punched there is bound to be a burr. I suppose it depends on the case manufacturer . The lee factory crimp suprised me. I've tried it and for some loads it actually does help.I think it helps square up the bullet with the bore since it works best with very light bullets in my .308.


November 25, 2006, 05:32 PM
About 12 years ago I got a deburring tool at a rummage sale. My 6mmRem hunting rifle is a heavy barreled, heavy stocked weapon that weighs 13 1/2lbs. The rifle would consistently shoot 0.26 to 0.31 5 shot groups with Sierra 85 gr HPBT (my varmint load). I selected 200 cases out of a batch of 1000 identical Remington cases (weighed volume checked) and deburred 100 of them. Loaded them identcally. At the range I alternated shots with each at their respective targets, and did this over 4 seperate trips.

The results were really inconclusive. The burred cases averaged 0.29, the deburred averaged 0.28. Both had best groups of 0.26 and both had largest group of 0.32. I now deburr all cases as standard practice.

November 25, 2006, 05:39 PM
Do your handloads match good factory loads for accuracy? If so I might not bother, if not I might try everything.

If your handloads don't exceed good factory loads by a wide margin, you're doing something wrong.


Smokey Joe
November 27, 2006, 02:00 PM
So, USSR--did you debur or not for that VERY nice group??

Cases made by Norma, Lapua, and Starline are drilled, not punched. If you use these cases, which are in all other ways very hi-quality, also, you don't have deburring as an issue about which to worry, and also you don't have to do the deburring yourself.

I use Norma or Lapua cases for my "serious" rifles, and Starline cases for my target centerfire pistol.

The rest of my arsenal gets whatever I can scrounge @ the range and I don't debur those cases.

November 27, 2006, 02:49 PM

LOL, I didn't do anything other than resize the once-fired M118 LR brass and chamfered the necks. I just wanted to see what the unworked on brass was capable of. That being said, I do normally debur and uniform the primer pockets on cases other than Lapua and Norma. It takes very little time and is a one-time operation on brass.


November 27, 2006, 04:47 PM
I do all mine but only because it's a fast operation to complete. I generally fight the tendency to add steps to reloading--if it involves an investment in time, it had better be something I can see on paper.


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