Flash hole deburring question.

[Fullthrottle]

Ok so I have been reloading for a while, not at all for competition but to have ammo that works well for me.(think availability).
I have a friend that I have been coaching to do some reloading of his own. But this guy has been researching faster than I have about getting more precision out of the ammo than I am.

He asked me today about flash hole deburring and what was the best tool. I have no answer as I have never gone that route or found a need, as of yet.

So my question is why is it needed? What is the purpose?

I have reloaded thousands of rounds over the last 5-6 yrs and have not done it.
What am I missing?

[243winxb]

http://www.thehighroad.org/showthread.php?t=614921 debur flash hole. I think some brass is drilled and other punched. Not all need it?? I guess its done so the flame from the primer is the same each time?

[Jim243]

For the most part it is not needed, however for rifle case prep, I tumble the cases a second time after resizing to remove the case lube. Often media will get stuck in the primer pocket and flash hole of the case and I remove it with a 5/64 drill bit used by hand. At the same time it will allow me to ream the flash hole and insure a even opening for the primer flame to go through and ignite the powder. Therefore all flash holes are uniformed for maximum ignition.

This way I do not have to worry about blocked or miss shaped flash holes and having a catastrophic failure with my rifle.

Just what I do.
Jim

[cryogenic419]

Flash hole deburring basically is just ensuring that all the flash holes have no material possibly obstructing the surrounding area of the exit side of the hole. Its generally not a problem but some folks do it to ensure uniformity across all their brass and to try to get rid of another variable in their quest for maximum accuracy. My take on it has been it allows for more consistent ignition and case capacity uniformity. I know, that tiny speck of brass really doesn't detract from capacity but somewhere in my mind I think it helps haha.

Be aware it only needs to be done once to the piece of brass and not all brass will even need it done. Its not a bad idea but just know that you aren't going to notice any dramatic accuracy improvements. What its going to give you is uniformity and consistency in your brass. There are folks who don't even bother doing it putting out accurate ammo, some folks who do it putting out accurate ammo, and some folks who do it that put out ammo that isn't so accurate. Just have to decide if its worth the effort for yourself.

As far as I know its mainly a rifle brass thing, not so sure people even bother with pistol brass.

RCBS, Hornady and Lyman all make decent inexpensive tools for this.

[AllenJ]

I started deburring flash holes a couple years ago using the RCBS tool. I've done 500-750 cases so far using Winchester, Remington, Barnes, and Norma brass. In all honesty I have only found a few of those cases that had a burr big enough to feel when deburring (all Winchesters). The concept of uniforming flash holes to get consistent ignition of the powder makes sense to me but for the average sporting rifle I don't think it means much.

[rg1]

Punched out primer flash holes sometimes leaves a bad burr. I just prefer to check all flash holes for any raised burr or a partially blocked flash hole. I don't cut or remove material and adjust my flash hole cutter to just touch the flash hole and remove any high burrs. I don't see many cases that need flash hole deburring but every now and then you'll find one. Maybe cleaning that case will prevent a flyer? Most all flashhole deburring tools are simply a #2 center drill available at most hardware stores and simply a shaft with about a 7/32" diameter which will fit in .224" case necks, drilled to accept the 3/16" body of the center drill, glue in or press in 1/2 of the #2 center drill and a handle on the rod end plus some type of stop collar. Look closely at most all flashhole deburr tools and you'll see the #2 center drill. So pick a tool with a good handle and stop collar as most all have the same cutter.

[wogpotter]

A while back I did a test with 20 (as close as I could make them) identical cases. Weighed, volume measured same brand/lot & so on.

10 were "match prepared" with all the bells & whistles used, the other 10 were just run through a progressive press.

results:
"match prepped load"

Date	Firearm	Cartridge	Bullet	Type	OAL	Case	Reload #	Trim #	Charge	Powder	Primer	Chrono Date	String #	Shot #	Ind. Vel.	Low	High	AVG	E.S.	S.D.	A.D.	Group/Distance

20-Mar-10	#4 Mk2 Fazackerly	.303 British	174 Gr Hornady	FMJ BT	3.0350	PPU	2	0	35.5	IMR3031	CCI 200	20-Mar-10	1	5	2237	2181	2238	2217.0	57.3	20.6	16.0	1.5"@100Yd.

"Standard load"

20-Mar-10	#4 Mk2 Fazackerly	.303 British	174 Gr Hornady	FMJ BT	3.0350	PPU	2	0	35.5	IMR3031	CCI 200	20-Mar-10	1	5		36	2267	2219 @ 10'	81.1	29.7	23.3	5"@100Yd.

Not just deburring I know, but more precisely prepared ammo really does shoot better enough that I'll do the extra work for the results.

[cw308]

I deburr the flash hole on all new brass. first size and trim the brass to the same length. When the flash hole is formed, they may have a burr on the inside, the deburring tool slightly bevels the hole for a consistant burn. Only needs to be deburred once. I feel preping your brass is one of the most important parts of reloading. Also uniform your primer pockets, I do this on every reload, makes priming a breeze.

[Bart B.]

Too many match winners and record setters don't deburr flash holes to make it worth my time. Tried it myself to find out; they're right.

[Longshot4]

I have been deburring flash holes for quite a few years now. I load for accuracy so why not. Some cases have more flash than others some flash holes are narrower or out of round that and the bevel should allow the flash of the primer to spread consistently. I now uniform the primer pockets so I don't have primers not seating and a uniform pocket. one time is all it takes to avoid high primers or tight primer pockets. I don't mind the small cost of the tools and I simply don't call it work. It's all a mater of going for accuracy and consistency in the cases. I loaded for a long time without uniforming primer pockets and excepted the primers fouling my revolver frame and primers not seating. Now it can't happen... Bart made his choice now you can make yours

[SVO]

I think uniforming flash holes and primer pockets is one of those feel good ideas. I've never seen a difference in group size or across a chronograph.

[Fullthrottle]

Thank all of you fine folks for the info.

Like I said I have not yet reloaded to get precision results, but I am working that direction. My friend I have introduced to reloading has been doing much research into this.
We will get there eventually and I will show him this forum full of good info!

[Unclenick]

I think it depends on the powder. About 20 years ago I tried loading Accurate 2520 spherical powder in my M1A. Accurate was bragging that it was called "Camp Perry powder" by competitors who liked it. The gun would shoot about 0.7 moa at 100 yards from slinged-up prone with any of several stick powder loads under the 168 grain SMK. The 2520 loads, though, no matter how I tweaked them, only shot about 1.25 moa.

So, one day I got a flash hole deburring tool for the first time, and though I'd intended it for bolt guns, I had to try the new toy out on something, and since I was putting more 2520 loads together for the M1A, that's where I tried it. Immediately the groups dropped to 0.7 moa, just like the stick powder groups. So then I tried it with the stick powders, too. No improvement with them. No difference at all.

2520 is a spherical propellant, and the older ones, in particular, tend to be harder to ignite than stick powder is. Clearly the hole deburring helped. I was using a standard primer at the time, and today I'd have tried a magnum primer, too, to see if that had the same effect, but at the time wasn't aware that CCI magnum primers had been reformulated specifically for the spherical ignition issue.

So, bottom line, it can help to deburr flash holes under some circumstances. The only way to be sure you don't have one of those circumstances is to try it.

The one other place I find I am using the deburring tool is with military brass I've run through my Dillon primer pocket swager. Even though it is drilled, military brass has burrs (their creation depends on the speed and feed rate of the drill and other variables). The Dillon's anvil tends to squash the burrs flat and that sometimes lays them over the flash hole to the point you see significant interference with light passing through. Those I deburr.

[Snyper]

I do it and it really doesn't take that long
It's amazing how much brass comes out of some cases, while others just have a couple of tiny chips

It may take a little time, but if I weren't reloading, I'd just be wasting it on something useless, like the internet

[Snyper]

Too many match winners and record setters don't deburr flash holes to make it worth my time.

I suspect the ones who don't are paying a lot of money for top of the line brass, and not just using standard factory run

[Bart B.]

I'm referring to regular factory brass; Winchester, for example. Not expensive stuff.

[F. Guffey]

I have JIC tools. I do not need them but 'JUST IN CASE". I have de-burring tools, occasionally I will dig one out and tapper the flash hole from the top, problem, I have never found a case that had a hanging chad or a burr left when it was drilled and or punched.

I also have a flash hole gage. It works if the flash hole diameter was measured before firing. Care should be taken when near and or handling de-burring tools. If when working with one and for some reason the user drops one, do not make an attempt to catch it, wait until it stops bouncing and or rolling.

F. Guffey

[wogpotter]

You're lucky!

Every time is process a batch of new brass I find several with "bits" that I have to remove. It doesn't seem brand specific either I've had the same results with Win, R-P, PPU & LC brass.

[pathdoc]

The tool was there when I was in the gun shop one day, so I bought it and used it on all my .303 brass. I'm not sure how much difference it made, but I figured my SMLE could use all the help it could get, given the distances I was shooting at.

Now? I won't get rid of it, but I'm not sure I would buy one unless I had a rifle that was already shooting under 1MOA. That being said, Wogpotter's reported results in .303 British do tend to speak for themselves. And like Wogpotter, there are cases I've used it on that I can FEEL something being ground off.

[mete]

IIRC my old Speer reloading book said
Deburr
Drill ignition holes so they are all the same dia
Ignition holes should also be the same length !

This for the most accurate shooting !

[Metal god]

I have never found a case that had a hanging chad or a burr left when it was drilled and or punched.

Me either but then again I can't see inside the case . How ever here is a pic of all the brass chips that came out of my cases after deburring 220 , 5.56 LC-14 cases .All cases were trimmed to with in + or - .0005 0f 1.750 . Some cases did not feel like anything was removed others I had to hold the case with pliers to keep them from turning while it was removing material . I've notice over the years while drilling many a hole that the drill bit tends to bind up like that when the hole is not uniform or it encounters a bur in the material it is drilling through

[F. Guffey]

I've notice over the years while drilling many a hole that the drill bit tends to bind up like that when the hole is not uniform or it encounters a bur in the material it is drilling through

while drilling many a hole

I am not sure we are talking about the same thing, I have reamers that de-burr, by design they extend through the flash hole from the inside out and align with the case neck. Sharp and pointed like an ice pick, I hold the case with my hand and turn the de-burring tool with a green plastic handle made by RCBS. Holding a case while drilling the flash hole with pliers?

I drill flash holes and primer pockets, I do not find it necessary to hold the case with a tool that is not case friendly.

F. Guffey

[F. Guffey]

Ignition holes should also be the same length !

Mete, That is a hard sell, I measure case head thickness from the top of the cup above the web to the case head. I have found a difference of .060" in thickness. I find there is an advantage to cases with thin case head thickness and an advantage to cases with thick case heads. To me .060" is enough difference between the two cases to sort.

F. Guffey

[Metal god]

Holding a case while drilling the flash hole with pliers?

No not using a drill . I have the Lyman flash hole tool and believe it's the same as the RCBS . Every once and a while the tool binds up and I can't keep the case from turning in my hand so I use pliers to hold it while still only hand turning the tool . I think that was twice out of those 220 cases prepped .

The drilling of many a hole in my life was a general statement saying do to my work I've drilled thousands of holes through every type of common material . I've had my share of drill bits bind up and in some cases almost break my wrist . IMHO it's almost always been do to the hole not being uniform and/or the drill bit binds on a bur or other obstruction . My point is I believe those cases that the tool got hung up in or even the cases that are harder to debur then others . They have some sort of issue with the flash holes . What that is exactly I don't know but believe I removed that problem while uniforming the flash holes .

[wogpotter]

Every once and a while the tool binds up and I can't keep the case from turning in my hand

I have a fix for you.

Run the part of the tool that goes inside the flash hole into the flash hole via the primer pocket but not so far in it chamfers the base of the pocket. Now give 1 full turn with no down pressure.

Reverse to the "normal" inside the case mouth position & proceed as normal.