Drilling out the flash holes in brass?

[Old colt]

I've seen guys talking about enlarging the flash holes in rifle brass when using small amounts of fast burning powder. I was just wondering the reason behind it? New to rifle bullet casting, I do load cast in 45 acp, 45 Colt, and 454 Casull. Thank you in advance.

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[too many things]

works good for the small charges and a flake type powder like reddot but make sure you mark them

[Dusty Bannister]

The purpose of enlarged flash holes is to prevent the primer pressure from pressing the primer partly out of the pocket when the round is discharged. With small powder charges, there is not enough pressure to expand the case mouth to grip the chamber so the case is blown forward by the primer pressure and some think the shoulder is set back. You might also have seen comments about doing this when making wax bullet cases for indoor short range pistol target practice.

[Half Dog]

I drill mine but only to make the brass closer to being the same. Mostly when I have mixed headstamps.

[Scharfschuetze]

It prevents shrinkage of headspace in bottle neck cartridges. With squib loads, the pressure in the primer pocket is actually higher than the pressure in the case. The pushes the case forward (and the primer back) which collapses the shoulder of the case to some extent. After a few loads of this type you start to see a marked decrease in HS, often to the extent to where the extractor is holding the case with the primer against the strike of the firing pin. While this is not dangerous, it isn't really a good thing for ballistic consistency.

I have tested this over decades with two different tools (Mo's and the Hornady HS gauge) and it always holds true. Enlarged FHs don't shrink, standard FHs shrink with very low pressure loads. My squib load brass with the enlarged flash holes are segregated and kept for these lighter than normal loads.

On one assignment of mine, I had access to an indoor range every day when I wasn't deployed. I and a good friend at the unit refined our squib loads to the Nth degree over the three year assignment.


You might also have seen comments about doing this when making wax bullet cases for indoor short range pistol target practice.

Right you are. While attending a police academy in the days before computer simulation, we fired wax bullets at training films projected onto large sheets of butcher paper. I also started my children off with wax revolver loads when they were learning pistol craft. Drilled FHs were mandatory or the revolvers would seize up.

[Tackleberry41]

Some drill, some dont. I looked around on the internet theres no agreement on it being required. Certainly no industry study to decide the issue. I have fired tons of pistol powder in high volume cases, like 8gr of S1000 in a 7.62x54r. Never drilled a flash hole, never had any issues.

[Don Fischer]

I have used Red Dot in my 30-06 with cast loads. Can't see any reason to drill out the flash holes.

[dverna]

I have thought about doing it for low charge weights in my .30 cals. but dread the consequences of getting cases mixed up. One option would be to get some nickel cases so you cannot screw it up. BTW, I have messed up trying to read the head stamp so I know that option will not work for me.

Don Verna

[6622729]

I have used Red Dot in my 30-06 with cast loads. Can't see any reason to drill out the flash holes.

I debur flash holes but I don't drill them oversize. Once in a while one actually gets drilled out a bit by the deflashing tool but that only brings it up to the normal size. I do find a lot of burrs in rifle brass. I don't mess with it for handgun. I use this Lyman tool.

184333

[country gent]

On rifle brass I deburr and uniform the primer pockets then uniform the primer pockets to depth and flattness. WHat I do to the flash holes would more accuratly be called reaming as I find the largest and cut the rest to it, normally only a couple thousandths. I made some wax bullet cases 38 spl. I did open flash holes to .110 but did it with a modified drill. I cut the flash hole and recut the primer pocket to large pistol size at the same time. This way I couldnt mix them up, even if they got in with standard 38s the small primer wouldnt seat. On the 45s I did I sleeved to small pistol as then there were no small primer 45s yet.

[gwpercle]

No need to do it on handgun brass.
Remember uniforming and deburring flash holes is one thing and OK to do in rifle and handgun.
Getting an oversize drill and enlarging may render them useless in normal loads.
The drilling out was common when using the primer as the only propellant in wax bullet loads. After enlarging these cases were safe only with wax , primers and no powder charge.

My advise is to not drill them out. Red Dot is not position sensitive , Unique does not seem to be either , I use both with cast and with no fillers or tufts of Dacron .
Gary

[Freightman]

Only time I drill flash holes is for dedicated glue boolit shooting the cases are always separated. Great fun in the back yard and deadly to nut stealing tree rats :Fire:

[Multigunner]

I made some wax bullets for my 1851 Colt replica by soaking tissue paper with candle wax and rolling into a ball while the wax was still warm.
With a full load of Black Powder I fired one at a old galvanized steel trash can that had a four inch layer of snow on the lid. All the snow was blown away and the side of the trash can looked like it had been hit with a hard swung ball bat.
I have a feeling that would not be a less than lethal load.

When firing very light round ball loads in an old airweight I found the spent primers always protruded enough to cause serious drag on the breech face.

When firing fairly light loads of 4198 in a 7.92 X57 the shoulder was set back a hair at every firing.

I ran across a study on drilling out flash holes awhile back. It was a detailed study including drilling off center flash holes to study the effect.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi_7prx1anRAhXhllQKHTG_DRoQFggdMAA&url=http%3A%2F%2Fscholarsmine.mst.edu%2Fcgi%2Fview content.cgi%3Farticle%3D8415%26context%3Dmasters_t heses&usg=AFQjCNFB5onfvntjxX11KB2nIbivsiIVPA

[Scharfschuetze]

That's a great study Multigunner and it closely parallels my testing.

I have tried my enlarged flash hole (FH) cases (Ex. for squib loads 110 grain 30 cal at 1,100 fps) v. standard flash hole cases in the 30/06 and the 308 with duplicate full power loads (worked up of course) to see if there was any danger of an overlooked large FH case with standard FH cases.

My results? Much like the author's study. Velocity was up a smidgen while ballistic uniformity was reduced. My tests were over a PACT chronograph with no pressure measuring. All obvious signs of pressure one looks for as a layman were absent with the enlarged FHs in comparison with the standard FHs.

In the end though, it's not difficult for an intelligent and careful man with reasonable vision to keep cases sorted and separated without resorting to obvious markings. So no worries there.


When firing fairly light loads of 4198 in a 7.92 X57 the shoulder was set back a hair at every firing.

I'm sure that you have already; but if not, you'll find that enlarged FHs with these very light loads will prevent the set back or shrinkage of the head space. Works a treat.

[Tackleberry41]

So wading thru that write up on flash holes, seems what we have been using forever is wrong, as in to small. One would imagine the flash hole hole size now used was arrived at by pure guesswork or because that was the cheapest easiest way to do it vs any actual scientific method applied. And some ammo is being sold now with even smaller flash holes.

And that a standard size for everything is wrong, where each ammo might require a different size for best accuracy, something Remington, Winchester etc is simply not going to do due to the extra cost and effort required.

So might be worth drilling a few cases to 3mm and see if you do get better accuracy. Wouldn't that be something, we go buy new brass then run them all thru a drill press to enlarge the flash holes, because the ammo companies simply refuse to do anything different.

[Scharfschuetze]

So might be worth drilling a few cases to 3mm and see if you do get better accuracy. Wouldn't that be something, we go buy new brass then run them all thru a drill press to enlarge the flash holes, because the ammo companies simply refuse to do anything different.

Tackleberry,

That is a logical conclusion and in many cases it is very true. In others, particularly with my 7.65 Mauser for some reason, it does not. I think like all loading endeavors, it's sometimes a flip of the coin with what works and what doesn't. Sometimes the difference in my 7.65 Mauser using upper level cast bullets (208 grain 311299 at 1,850 fps) can be well over a minute of angle larger or smaller. This is with SR 4759 powder. A different powder may well have produced the opposite result. Adjusting flash hole size is definitely another tool that we can use for accurate ammo, particularly at the squib or ultra-light levels where I have found it most useful for accuracy and maintaining a bottleneck case's head to shoulder measurement (headspace).

Tradition is a strong factor in the shooting sports. Things like your observation of flash hole size as well as rifling twists for certain calibres, et cetera. are all pretty well ingrained into both the shooting public and the corporate gun business.

Here are some examples with 10 shot groups at 50 yards. Small FH: smaller group. Large FH: larger group

[Tackleberry41]

[QUOTE=Scharfschuetze;3899633]Tackleberry,

That is a logical conclusion and in many cases it is very true. In others, particularly with my 7.65 Mauser for some reason, it does not. I think like all loading endeavors, it's sometimes a flip of the coin with what works and what doesn't. Sometimes the difference in my 7.65 Mauser using upper level cast bullets (208 grain 311299 at 1,850 fps) can be well over a minute of angle larger or smaller. This is with SR 4759 powder. A different powder may well have produced the opposite result. Adjusting flash hole size is definitely another tool that we can use for accurate ammo, particularly at the squib or ultra-light levels where I have found it most useful for accuracy and maintaining a bottleneck case's head to shoulder measurement (headspace).

Tradition is a strong factor in the shooting sports. Things like your observation of flash hole size as well as rifling twists for certain calibres, et cetera. are all pretty well ingrained into both the shooting public and the corporate gun business.

Here are some examples with 10 shot groups at 50 yards. Small FH: smaller group. Large FH: larger group[/QUOTE


Its something to try. At worst I ruin a few cases.

[BAGTIC]

The case is driven forward by the striker/firing pen. Too large a hole can exaggerate primer setback. If the load is a weak/low pressure one it may not back the case up far enough to reseat the primer. I revolvers this can interfere with cylinder rotation.

[Bodean98]

This is the most accurate answer I have found on the subject!
http://castboolits.gunloads.com/showthread.php?152431-Recipes-for-quot-Mouse-Fart-quot-Loads-in-30-06&p=1703746&viewfull=1#post1703746

[shunka]

Greetings Gents -

As far as seperating out modified cases, I use cold blue to die the entire case. Generally I am using these for experiments (and permanently mark the case heads) , or as dedicated cases with drilled-out flash holes used with wax or hot-glue gallery rounds.
The blackened case is immediately apparent!

Scharfschuetze (http://castboolits.gunloads.com/member.php?23645-Scharfschuetze) - have you written up your findings, and are they available? I would love to peruse them as I engage further in low-power gallery and training loads!

yhs
shunka