Primer "hole" size?

[Prof Young]

Loaders:
Was sorting some range brass and noticed this. (see pic below)
So, does the size of the hole in the primer pocket make any kind of difference?

Life is good.
Prof Young

[Zeroed]

I was reading about that last night. Large/Small primer hole. Was a good write up on it. Originally thought that the smaller hole would give a laser (tighter diameter) type fire thru the powder for a more fast consistent velocities. Some still think it doesn't, while others say yes. Even had pics of the fire coming out of the (primer only) casing, measuring the length of the fire.

[Mike38]

I believe that's called a flash hole. Not to be confused with the hole my wife calls me.

[Yosemite Steve]

That's a pretty huge difference.

If it were me I would load up some rounds with each type of brass and record differences. I am interested to know more about this.

[hounddawg]

I have seen some of that in pistol before but no idea why. Will a normal .080 depriming pin fit through the small one?

If that were a rifle case I would say it is a Palma size flash hole or .059 size hole. Longer primer pocket life and better ignition in the longer rifle case in theory.

Being that it is pistol I would have to think it was for ignition purposes being that pistol cases tend to have a lot of space inside the filled case. Larger hole would make a wider flame maybe and give a more uniform powder burn. Just guessing here

[Zeroed]

Prof Young,
This is the site I was reading about this. But it is "flash-hole" as Mike38 stated, but I found it when googling large vs small pocket size.

http://bulletin.accurateshooter.com/...308-win-brass/

Hope this helps.

[243winxb]

Large flash may increase velocity?

See primer size vs velocity, large vs small primers in 45 acp.
https://www.starlinebrass.com/articl...-Large-Primer/

[mikld]

Larger flash holes are used for NT primers (non toxic) which require a larger flash hole to insure good ignition. Too large a flash hole can increase pressure on the primer and fore it out of the pocket. I've found some 45 ACP brass marked "NT" on the headstamp to have larger flash holes and some used small pistol primers...

[T. O'Heir]

The flash hole doesn't make enough difference to matter in handgun cartridges. It might for BR shooting, but it's unlikely.
It has nothing whatever to do with velocity being consistent or not though.

[hounddawg]

Thanks to the OP for opening an interesting discussion. I think I have learned more about primers and primer cups in the last few hours than I could imagine. There is a 3 part article by Laurie Holland editor of in Target Shooter Magazine where she does a indepth primer review including small primer and small flash hole vs large rifle primer tests. I found it earlier and plan on doing a reread or two later on.

It's one of those articles I read then reread a couple of times and discover something new each reread. It seems obvious that the choice of primer make and size can make a major difference in velocity standard deviation and group sizes even at close range

SMALL RIFLE PRIMER PERFORMANCE IN THE 308 PALMA CASE BY LAURIE HOLLAND

Part1- http://www.targetshooter.co.uk/?p=2613

Part 2- http://www.targetshooter.co.uk/?p=2621

Part 3- http://www.targetshooter.co.uk/?p=2613

I am doing a load workup on my .260 this week with some Peterson brass with the Palma style small primer and small flash hole early next week. Looks like I will be playing with the make and model of the primers also

[Prof Young]

Thanks for the good links to informative articles. So much to learn! It's called a flash hole. Right. I knew it had a name but didn't bother to figure that out.

Life is good.
Prof Young

[Nick_C_S]

I've made the observation that Federal's 45ACP flash holes are larger than others. I load as usual. Haven't noticed any difference. Haven't conducted any scientific tests, either.

[Emerson Biggies]

I was researching a similar thing at the SAAMI site last week. Their mechanical drawings of the 223 Remington case does not have a specification on the flash hole. Further checking of other brass in my possession was also without data. You'd think the flash hole would be part of the data package for any caliber. Go figure.

[WhyteP38]

Will a normal .080 depriming pin fit through the small one?

It depends on the type of pin you're using. A flat-tipped depriming pin will usually jam in the flash hole. I've had that happen while depriming once-used Guat 5.56 surplus. A rounded-tip depriming pin will usually knock out the spent primer without jamming in the flash hole but will jam about 25% of the time.

[rclark]

I toss my .45 ACP with the large flash holes. I found I was having pierced primers that would tie up my revolvers. Normal flash holed cases never had that problem.

[RC20]

This is just my wandering mind.

In the old days it was a flash hold because that's where the trail of powder went in a gun.

The terminology never changed but in reality it is a Primer hole.

Technically if the powder cover the hole, grains are small enough (ball) then you have a short trail of powder.

I managed to get a case into a group with no primer a while back, nothing came out the primer hole.

So, If a man says something in the forest and there is not a woman to correct him, is he still wrong?

[hdwhit]

Prof Young
...does the size of the hole in the primer pocket make any kind of difference?

While each brass manufacturer determines the size of the flash hole, there are three sizes that predominate among boxer primed brass. Most boxer primed brass encountered in the United States uses the largest of the three. Decapping pins designed for that larger flash hole may bind in a smaller flash hole.

As far as the effect of the flash hole size on ignition, it may be enough to be a concern to the shooters looking to shoot five-shots and end up with one-hole, but I have never noticed any difference in ignition reliability, velocity or variability of velocity on any of my ammunition (as determined by a 1992 vintage Shooting Chrony). In my experience there has been more difference between primer brands than there is in using the same primer brand with differing flash hole sizes.

Of course, if having smaller than normal flash holes causes a problem, you could always get an appropriate sized drill bit and drill the flash holes out.

[hounddawg]

[

The flash hole doesn't make enough difference to matter in handgun cartridges. It might for BR shooting, but it's unlikely.
It has nothing whatever to do with velocity being consistent or not though.

I suppose it doesn't if your idea of a good group is 1 inch at 25 yards then it does not matter. But for precision shooting it certainly seems to

I would not recommend drilling them out either. If you are buying Palma style cases then it should be expected they will have .060 flash holes

many Lapua small flash-hole case users won’t touch them as opening them out significantly invites increased velocity spreads and group dispersions.

http://www.targetshooter.co.uk/?p=2613

[LOLBELL]

Now that is a write up. I could not type that many words in two days. ALOT of good information in it.

[RC20]

Now that is a snoot full. Be interesting when Unclenick weighs in.

I struggle with veracity when you see things like moisture will do in a primer though and we know they are pretty impervious.

Is there such a thing as a cool dry place in Mississippi short of a fridge?

I wish the write would say, keep as reasonably dry and out of the direct sunlight as possible.

Is exploding plastic cases more desirable than metal?

It would be good to be clear Primers are an explosive and smokeless powder is not.

I would not want to pack any case full of an explosive metal or not.



And Aside:

We were home remote taught correspondence course on a State program where we lived for a few years (no school)

They had us write 3 times a week a two page report.

To this day I can write a two pages report on a nail (not that it would be interesting!)

Rebellion ensued one lesson when they forgot to include a male related subject and the directive for that report was My Favorite Doll.

My mother was a very capable and smart woman, came up with a replacement subject and included a note to the administrators that they needed to pay attention, facing a rebellion of 4 hard headed boys was not in a parents best interests.

[hounddawg]

Now that is a write up. I could not type that many words in two days. ALOT of good information in it.

amen to that, nice info

I have been having some issues with Winchester LR burning small holes at the edge of the primer cup and the primer. Had to toss the brass and replace 2 bolt faces where they had been pitted from the flame. Shoot the the same load using brass from same lot with CCI 200's and no issues. I think that article explained why

[flashhole]

I had to weigh in on this thread because of my moniker.

I did not type it. I cut and pasted it. Don't remember where I got it but it's in my archives.

I actually had to delete some of the article because it went beyond the 30,000 character limit. I deleted the 50 BMG section.

[Zeroed]

Quote by Flashhole: I actually had to delete some of the article because it went beyond the 30,000 character limit. I deleted the 50 BMG section.

I'd be interested in reading all of it, If you have the time, could you send the deleted stuff to me in a (or multiple) PM?

I've already saved the above stuff. Thanks

[flashhole]

Large Rifle Magnum

CCI 250
CCI #34 - commercial version of the fully-qualified DOD primer for use in U.S. military ammo.
Federal 215 - original magnum primer
Remington 9 ½ M - mildest magnum primer.
RWS 5333
Winchester WLRM
Wolf Large Rifle Magnum LRM - all brass

50 BMG

CCI #35 - commercial version of the fully-qualified DOD primer for use in U.S. military ammo.
Winchester 8312

Primers recommended for use in .223 Rem/5.56 semiautomatic rifle loads:

CCI #41, 450, BR4 (#41 & 450 good with ball powder)
Federal 205, 205M
Remington 7 1/2 BR (good with ball powder)
Winchester WSR (good with ball powder)
Wolf SRM (good with ball powder)
Wolf SR223 (hotter than SRM - great with ball powder)

Primers recommended for use in .308 Win/7.62x51/7.62x39 semiautomatic rifle loads:

CCI #34, 200, BR2, CCI 250
Winchester WLR, WLRM (good with ball powder)
Wolf LR

[Unclenick]

Flashhole,

It looks like you escaped reading the board policy on posting copyrighted materials. Due to past lawsuits against boards for copying articles, this is not allowed on the board. It's too bad, but to avoid being sued, it had to be done. Probably a maximum of a couple of paragraphs will fall under Fair Use Doctrine, but that's all you can do other than direct people to the source information.