Flash hole deburring question.

[wogpotter]

I built up a small pile of cuttings,

Exactly those are what you removed which is why we do it.

[243winxb]

Before and after. Federal 30-06 Brass. Looks like brass in the flash hole will spring back after being formed. May be best to remove, if shooting benchrest?

[wogpotter]

DANG! Now that's what I call a burr! Looks like a lunar crater!

[Bart B.]

I wasn't amazed in the amount of brass that came out of .308 Win cases trimmed to 2.000" length. My RCBS flash hole deburring tool removed a lot more brass from flash holes in thicker heads than thinner ones.

In my tests with the same load recipies, those with deburred flash holes shot no more accurate than those without deburring having varying amounts of hanging chad. That's with 20-shot test groups at 600 and 1000 yards.

In the pictures above, the deburred hole appears to have a lot of "enhanced chad" at the 4:30 o'clock position and is high enough to case a pronounced shadow. At 11:00 o'clock, it's non-existant and the edge of the cut is flush with the bottom of the case; the way flash hole deburring tools should debur. I think that hole's not 100% deburred; perhaps only 30%.

[Magnum Wheel Man]

I'm not a competitive shooter... but I do reload a lot & a lot of different calibers...

I find the smaller the cartridge the more difference it makes... 22 Hornet, ( I find a lot of punched flash holes with burrs ) but I see way more difference on the 22 Hornet than I do on 243 ( for example ) it's possible the differences are just that the percentage of opening / restriction / case weight etc. is more on a smaller case than a bigger case...

also are you using matching head stamp / lot number brass... on hand loads for my 25 ACP revolver, I've bough much range brass, & sorted by head stamp... I'm using R-P cases, & they probably range from 4-5 decades of manufacture...I have a flash hole measuring tool, & I've found at least 3 different flash hole diameters... would that make a difference in 30-06... hmmm... maybe... does it make a difference in smaller cases like 22 Hornet ( or in this case 25 ACP ) yes... I can cut group sizes nearly in half by standardizing the flash holes in the 25 ACP

I use a Lyman flash hole uniforming tool, that I removed the handle, & screwed into my RCBS case prep center... & in 600 25 ACP cases I have a pile of brass probably 5-6 times bigger than the shavings pile pictured above... & I agree with Bart, the tool needs adjusted until the flair on the bit reaches the case head to eliminate the burr in the inside ( that burr may actually do more harm than the undrilled flash hole to start with )

I'm not sure if the OP posted the cartridges loaded, but if they are 223, & you are using mixed head stamp or mixed lot cases, I uniform & de-burr the flash hole... I've not really noticed enough difference on something like the 243 or 270 Winchester to uniform & de-burr... at the distances I shoot ( only up to 300 yards ) but I'm sure my OCD will kick in after I get all the small guys done, & I'll just work my way to the big ones

[243winxb]

Adjusting the tool to get the .010" deep cut, its not easy to do. Here is my 2nd attempt. Better? Even harder to get a usable photo. Using handle on tool.

[Magnum Wheel Man]

I've never micro zoomed or cut my cases, but that looks like as good a compromise as you can get... there is still a little bit of a burr, but you're also starting to get more bevel...

that's about where I'd set mine...

IMO, if there was a cutter that had a flatter transition, rather than that taper, it would do a better job... but the Lyman tool is what I'm using also...

BTW... are you still using the handle, or have you motorized it in some way ???

as mentioned, it fits nicely into a motorized RCBS case prep center

[Bart B.]

Has anyone tried using a #42 (.0935") through #46 (.0810") twist drill shank to measure flash hole diameters, then use the next larger diameter (smaller size number) from what just fits in to uniform all the hole diameters?

I've done that and if the bit's spun fast enough, it leaves little chad around the slightly enlarged flash hole. And it make the primer's flash diameter uniform. While some people think this is as important as "coning" the flash hole's inside shape, I've not seen any significant difference in accuracy. Which leads me to believe there's more spread in primer flash than what a couple thousandths spread in flash hole dimensions cause.

[243winxb]

There is about .003" burr left with the new setting on the cutter. The web average thickness is .2005" - 6 pcs. The last photo measures .203" There are 2 or 3 different diameters of flash hole last i check.

[wogpotter]

I set a little shallower than that. To me its more about removing chaff from the hole than creating some kind of venturi nozzle. I'm just about to cut the handle of my RCBS so I can chuck it in an electric screwdriver.

What I found with primer pocket uniformers is that slower revs & fairly light pressure works better than stop-start hand turning or high speed electric drill speeds or heavy pressure. I'm hoping that will translate to flash-hole reaming.

FWIW Lowes has a hex fit electric screwdriver chuck for about $15.00 well worth it, for me at least, as it lets me use any round-shafted item up to 1/4" dia.

[Archie]

I have the Lyman tool for this. I only process the brass for certain calibers and rifles.

I seriously doubt deburring the flash holes is going to make much difference in many firearms and calibers. For off the shelf guns, I would not bother. For those arms that are prepared and calibrated for utmost accuracy, this sort of thing cannot hurt.

At the risk of offending High Power Rifle shooters, the NRA National Match Course for rifles does not demand the same accuracy requirement for rifles and ammo as does Benchrest competition. For High Power Rifle, the 10 ring is seven inches in diameter and the X ring is three inches at 200 yards. For Benchrest at 100 yards, any group larger than half an inch is not competitive.

(Then again, High Power Rifle shooters shoot the 200 yard phase standing up on their hind legs, like a man. Benchrest shooter are hunkered down over a reinforced table with all manner of rests, pads and doodads.)

I don't deburr cases for my .22 Hornet, but now, Magnum Wheel Man comes along and claims experience! I may have to try it.

Happily, it only needs doing once.

[Bart B.]

Archie says:

At the risk of offending High Power Rifle shooters, the NRA National Match Course for rifles does not demand the same accuracy requirement for rifles and ammo as does Benchrest competition.

I disagree; especially if one wants to be ranked at the top, win matches and set records. But that's a popular belief.

The accuracy the high power rifle match winners and record setters get with their rifles and ammo tested properly equals what the benchresters get. But the size of the groups they shoot on paper are, at best, 1 to 3 MOA bigger than the rifle and ammo accuracy at target ranges. Nobody holds a hand-held shoulder-fired match rifle perfectly still and the same way for each shot like free-recoiling benchrest rifles are when they're fired.

Best example of this is when one of them tested his 600-yard loads and got several 10-shot groups around an inch. Then put a 40-shot group into under 2 inches. Pre-'64 Win 70 action, wood stock, Hart barrel, full length sized cases and 2.5 pound trigger; rifle clamped in a free recoiling machine rest eliminating all human variables. He won all the 600 yard matches at the Nationals that year shooting groups about 7 to 8 inches from prone.

Top ranked high power match rifle shooters have been full length sizing their fired cases for decades producing "benchrest" level of accuracy. A few years ago, most benchresters finally switched from neck only over to proper full length sizing their fired cases and realized the benefits of it. The best of both disciplines shoot inside about 1/4 MOA at 200 yards, 1/3 MOA at 300 and 1/2 MOA at 600 when properly tested in free recoil for accuracy.

[hot chili powder]

Been reloading for 270 & 30/06 for over 30+ years and the only thing I ck the flash hole for is that it's still a round hole

[Metal god]

Well post #52 and these pics sure should make people rethink the bur and chad ideas .




Now those are just 3 of the 6 I trimmed down to get a good look . Already 50% of cases have some sort of bur . out of the 6 there were 4 different head stamps and 2 calibers . I found burs so fast while just grabbing from a bag of brass I felt no need to keep looking for more

I'm not saying those burs will hurt anything but 243winxb's post and now mine clearly show the flash holes have burs . What effect they have when the round is fired may still be up for debate but one mystery has been solved

[243winxb]

Nice photos. The area from the bottom of the 30-06 primer pocket to inside the case is only .068" thick, if my estimated measurement is correct. Sure dont want to make a cut thats too deep.

[wogpotter]

I find the division of "Always something there" to "Chads? I see no chads!" interesting.

I find burrs & other faults fairly regularly, but not "Never" or "Always".