Brass Experimentation Question

[Ledd Slinger]

I just finished reading a post about a guy mentioning finding brass flash holes off centered. Interesting, but no noticeable negative effect caused with accuracy when he reamed them to the center thus creating a larger "egg" shaped flash hole. So I drifted off in silent thought about flash hole uniforming, then another thought about the pros and cons of standard size and PPC size flash holes.....etc.

I ended up with a final thought that begged me to question you fine folks if any of you have ever experimented with reaming out brass flash holes to a significantly larger diameter?

I can't think of any possible hazards in trying this experiment. The cup sits on the perimeter of the pocket and a larger flash hole would actually spread the force being applied on the primer from the powder blast to a larger surface area of the cup. It may even allow for higher pressure loads to be utilized. Many shooters bush their firing pins to disrupt a smaller area on the cup during the primer strike which increases the integrity of the cup to resist powder piercing from high pressure loads. So in essence, you would be creating the same effect of bushing a firing pin by enlarging the flash hole right?

I'm really bored overseas and just thinking of random things... What are your thoughts on pros, cons, and possible hazards of this experiment?

 

[savagedasher]

I just finished reading a post about a guy mentioning finding brass flash holes off centered. Interesting, but no noticeable negative effect caused with accuracy when he reamed them to the center thus creating a larger "egg" shaped flash hole. So I drifted off in silent thought about flash hole uniforming, then another thought about the pros and cons of standard size and PPC size flash holes.....etc.

I ended up with a final thought that begged me to question you fine folks if any of you have ever experimented with reaming out brass flash holes to a significantly larger diameter?

I can't think of any possible hazards in trying this experiment. The cup sits on the perimeter of the pocket and a larger flash hole would actually spread the force being applied on the primer from the powder blast to a larger surface area of the cup. It may even allow for higher pressure loads to be utilized. Many shooters bush their firing pins to disrupt a smaller area on the cup during the primer strike. So in essence, you would be creating the same effect of bushing a firing pin by enlarging the flash hole right?

I'm really bored overseas and just thinking of random things What are your thoughts on pros, cons, and possible hazards of this experiment?

The diameter of a hole increase in volume with small changes in size . The case manufacturers have a reason for the size .
Larry

 

[Ledd Slinger]

The diameter of a hole increase in volume with small changes in size . The case manufacturers have a reason for the size .
Larry

Ya don't say...

What you're missing is that they use a "one size fits all" flash hole. From 22 Hornet to 338 Lapua and everything else, small rifle primers and large. So that throws your theory of a "reason for the size" out the window. I believe flashole sizes could be an adjustment area of tuning in load testing. Small incremental diameter adjustments. Just like we do to test neck tension and seating depth.

 

[jlow]

I just finished reading a post about a guy mentioning finding brass flash holes off centered. Interesting, but no noticeable negative effect caused with accuracy when he reamed them to the center thus creating a larger "egg" shaped flash hole. So I drifted off in silent thought about flash hole uniforming, then another thought about the pros and cons of standard size and PPC size flash holes.....etc.

I ended up with a final thought that begged me to question you fine folks if any of you have ever experimented with reaming out brass flash holes to a significantly larger diameter?

I can't think of any possible hazards in trying this experiment. The cup sits on the perimeter of the pocket and a larger flash hole would actually spread the force being applied on the primer from the powder blast to a larger surface area of the cup. It may even allow for higher pressure loads to be utilized. Many shooters bush their firing pins to disrupt a smaller area on the cup during the primer strike which increases the integrity of the cup to resist powder piercing from high pressure loads. So in essence, you would be creating the same effect of bushing a firing pin by enlarging the flash hole right?

I'm really bored overseas and just thinking of random things... What are your thoughts on pros, cons, and possible hazards of this experiment?

The first thing I think of when I see a post like this is how much we should trust that comment “a post about a guy mentioning finding brass flash holes off centered. Interesting, but no noticeable negative effect caused with accuracy when he reamed them to the center thus creating a larger "egg" shaped flash hole”

A LOT of people do experimentation (AKA muck around) but most either don’t know how to properly conduct an experiment or have the tools and load to detect something when it does have an effect. The point is if one is going to do something BASED on someone else’s observation, that is always risky. I think the proper course of action is to always repeat what they did (if it is safe) and see what you get before extending your hypothesis/action.

 

[Ledd Slinger]

The first thing I think of when I see a post like this is how much we should trust that comment “a post about a guy mentioning finding brass flash holes off centered. Interesting, but no noticeable negative effect caused with accuracy when he reamed them to the center thus creating a larger "egg" shaped flash hole”

A LOT of people do experimentation (AKA muck around) but most either don’t know how to properly conduct an experiment or have the tools and load to detect something when it does have an effect. The point is if one is going to do something BASED on someone else’s observation, that is always risky. I think the proper course of action is to always repeat what they did (if it is safe) and see what you get before extending your hypothesis/action.

I'm not saying what he did or his results were a correct or good practice. I know I sure as hell wouldn't want an "egg" shaped flash hole. I'd leave it off center and use the brass for low pressure foulers or maybe even throw it away depending on the severity before I ever did that. Im wise enough to understand the risk in side loading pressure off center on a primer. I would hope most other folks are as well. I was just stating what I was reading that sparked my thought process down the road to this point.

 

[Rsadams]

I was always told not to increase flash hole size. But I to wondered why not. My dealings we're mostly with small pistol such as 9mm though. I always though it increases pressure in small cases..Altho I could be totally wrong.. I just don't do it. Better to be safe than sorry in my opinion..

 

[jlow]

There is always the theory that you want a weak flame from your primer so that you can set the powder alight progressively from front to back. This I think is the reason why German Salazar recommend the Russian primers. So the question is if you widen the flash hole would that not increase the size of the primer flame?

 

[Lapua40X]

Professionals in the business of manufacturing ammunition have access to laboratories, complete with specialized equipment, where they can test their products for optimum "safe" performance. I doubt that they punch out a piece of brass, punch a random size hole in its base and call it good. An occasional off center primer flash hole can occur in mass production but, even if it's off center, it's uniform in size. The research you're interested in has already been done:

http://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=8415&context=masters_theses

 

[Sniper338]

Powder is suppose to burn from the back of the case towards the bullet. Yes does this fast, but its a controlled burn. Throwing more flame into the case, depending on density if powder can cause an explosion and not a burn. Many folks drill out primer pockets for subsonic loading to increase the flame for the smaller amount of powder.

Imo the brass in the primer pocket is a safety. A bigger hole means more preasure back on the primer itself.

It all works the way it is all designed. Look at all the records being set... no reason to mess with flash holes to try to tune when you cant even load ammo good enough to compete with the best anyways..

 

[Shynloco]

There is always the theory that you want a weak flame from your primer so that you can set the powder alight....... So the question is if you widen the flash hole would that not increase the size of the primer flame?

Ledd,
It strikes me that if my feeble memory serves me correctly, this very subject about flashhole size was addressed in a study conducted like two/three years ago or so, the results of which were posted here. And those results concluded that a faster burn of the powder caused by a larger flashhole were counterproductive to accuracy. Might I suggest you enter "Flashhole enlargement" (or something along those lines) in the "Search" block and see if you can find that study for details and info.

Alex

 

[Berger.Fan222]

Imo the brass in the primer pocket is a safety. A bigger hole means more preasure back on the primer itself.

It all works the way it is all designed. Look at all the records being set... no reason to mess with flash holes to try to tune when you cant even load ammo good enough to compete with the best anyways..

That's a good point. If one is inclined to experiment with bigger flash holes, in addition to a good experimental design with only one independent variable and due care in observing effects on accuracy, speed, and consistency, one would probably do well not to push pressures above max.

But on the whole, reloading already has a bunch of variables: too many in my view to really understand the impact of changing each one. My inclination is to experiment more with the ones that are more likely to improve load accuracy and consistency.

 

[Ledd Slinger]

Good points. Will read up on the two experiments mentioned

 

[jlow]

Ledd,
It strikes me that if my feeble memory serves me correctly, this very subject about flashhole size was addressed in a study conducted like two/three years ago or so, the results of which were posted here. And those results concluded that a faster burn of the powder caused by a larger flashhole were counterproductive to accuracy. Might I suggest you enter "Flashhole enlargement" (or something along those lines) in the "Search" block and see if you can find that study for details and info.

Alex

That's basically the jest of the German Salazar study....

 

[M-61]

Professionals in the business of manufacturing ammunition have access to laboratories, complete with specialized equipment, where they can test their products for optimum "safe" performance. I doubt that they punch out a piece of brass, punch a random size hole in its base and call it good. An occasional off center primer flash hole can occur in mass production but, even if it's off center, it's uniform in size. The research you're interested in has already been done:

http://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=8415&context=masters_theses

I could not agree with you more. You doubt they (manufacturer) "punches" a "random" size hole? I am sure there is nothing they do that is 'random'.
Also my anecdotal information has shown that in some cases a smaller flash hole (for whatever reason) seems to promote better accuracy. So me a larger hole may be going in the wrong direction to start with. What happens when the flash hole is so large it can only keep the primer from falling inside the case? I don't have a clue, but what was stated above regarding professionals, labs, and equipment......well, I'll let them figure it out.

 

[Webster]

I just finished reading a post about a guy mentioning finding brass flash holes off centered. Interesting, but no noticeable negative effect caused with accuracy when he reamed them to the center thus creating a larger "egg" shaped flash hole. So I drifted off in silent thought about flash hole uniforming, then another thought about the pros and cons of standard size and PPC size flash holes.....etc.

I ended up with a final thought that begged me to question you fine folks if any of you have ever experimented with reaming out brass flash holes to a significantly larger diameter?

I can't think of any possible hazards in trying this experiment. The cup sits on the perimeter of the pocket and a larger flash hole would actually spread the force being applied on the primer from the powder blast to a larger surface area of the cup. It may even allow for higher pressure loads to be utilized. Many shooters bush their firing pins to disrupt a smaller area on the cup during the primer strike which increases the integrity of the cup to resist powder piercing from high pressure loads. So in essence, you would be creating the same effect of bushing a firing pin by enlarging the flash hole right?

I'm really bored overseas and just thinking of random things... What are your thoughts on pros, cons, and possible hazards of this experiment?

No mention of the case brand and caliber for the off center flash hole. How about the Berdan two flash hole cases? Where the cases from a strange WWI rifle? The best short range bench rest shooters routinely shoot 100 yd. groups around 0.200”. The 1000 yd. record is a 5 shoot group about 3.5” in diameter. All done with standard flash hole diameters. Can you shoot good enough to see a 5% improvement with a rifle that can shoot groups under 0.200” or even 0.500” groups? People never mention that the biggest improvements come from shooting technique. If you cannot read conditions and don’t have good gun handling the best rifle and reloads won’t give good groups on the target.

 

[Riesel]

There is always the theory that you want a weak flame from your primer so that you can set the powder alight progressively from front to back. This I think is the reason why German Salazar recommend the Russian primers. So the question is if you widen the flash hole would that not increase the size of the primer flame?

Let's go over that weak flame thing. I remember reading an article a long while back that German did on flash holes and large and small primers with some actual camera shots. Thinking was the small primer small flash hole would throw the flame out farther, twas not to be. I don't recall the comments made about the Russian primers and I usually do different primers when developing loads. Really never see much of a difference................until......I was working up loads for a 25-45 Sharps using H335 powder. The Russian primers designed for the .223 starting putting the 75 grain Hornady's in one three shot hole. That using 28.5 grains and I tested CCI BR and reg primers as well as Remington and Winchester. Maybe the "weaker" flame on the full case of H335 results in a smoother curve and not a violent jolt. I know the primer cups are holding up much better to the pressure.
Maybe This??

 

[mac86951]

In a steady state of pressure equilibrium the force on the primer is the same regardless of flash hole size. In the dynamic conditions of ignition, the flash hole size sets the rate at which pressure is applied to the anvil, which then redirects to the cup. Certainly PPC, vs. small primer flash hole sizes; the driving factor is the initial ignition focusing of the flash hole; secondarily the pressure constriction in reverse. I would think that within bounds, that minor adjustments are fine since many of us ream flash holes; and doubtful were within 0.0005" of each other.

Interesting topic; I may pursue further. I have a cartridge that I shoot with both large and small primers; based off of 7.62x39.

Could make for an interesting experiment within reason.

-Mac

 

[ebb]

Is this for real? I posted about some PPU junk brass I bought cause a few years ago I couldn't get anything else. All I wanted to achieve was to get the decapping pin to go through the flash hole and not hit the inside of the case so I could size the brass. Obviously this was a less than perfect situation, it seems to work however. I DID NOT preform a scientific test but all bullets did hit the target, and it looked to me like they grouped as well as the Winchester brass that I found later. I do not condone or encourage any little mad scientist to blow up their guns trying to beat the world record with 1/4 inch flash holes. I posted this so anyone buying PPU brass would know that IT IS NOT AS GOOD AS LAPUA at this point. Maybe they will fine tune their process and it will be at a later date. The flash hole tool was a hand made item that I bought at Ron Hoen's shop in St Lewis it had a specific purpose that I cant remember at this time but with it's little pilot it will center a flash hole and I think it will make it .062. DO NOT SCREW WITH YOUR HOLES BRASS OR OTHER WISE and don't mess your S--t up cause you read something I posted and have no idea why i did what I did.

 

[spclark]

Doesn't 6PPC brass come with a 0.060" dia. flash hole? I hear it's the most popular cartridge amongst BR shooters out to 200 yards? I don't shoot BR so I can't say I have first-hand knowledge, but I know a bunch of folks shooting 6BR's & Dashers than use 0.063" so there's something goin' on with a little hole in cartridges known for accuracy.

Few years back I bought a case of Speer 45ACP loaded with 180 gr JHP ('flying saucer' I think that bullet was nicknamed? They stopped making it since.) About 20% of those cases had flash holes that weren't much smaller than the primer pocket... but on paper shot just the same as the 0.080"-hole brass that came in the same boxes.

 

[Ledd Slinger]

No mention of the case brand and caliber for the off center flash hole. How about the Berdan two flash hole cases? Where the cases from a strange WWI rifle? The best short range bench rest shooters routinely shoot 100 yd. groups around 0.200”. The 1000 yd. record is a 5 shoot group about 3.5” in diameter. All done with standard flash hole diameters. Can you shoot good enough to see a 5% improvement with a rifle that can shoot groups under 0.200” or even 0.500” groups? People never mention that the biggest improvements come from shooting technique. If you cannot read conditions and don’t have good gun handling the best rifle and reloads won’t give good groups on the target.

Yes I know how to do all that. Im no novice to shooting. Shot 1K BR a few times. Great people, learned a lot, but kind of boring. Never went back. Got a $800 high quality front rest with all the bags and a new 1K BR rifle in the safe that i built 3 years ago and it hasnt had a single load development session at the range. Probably turn it into a varmint gun. There was a 1K BR record shot with 10 shots that was well under 3" (2.6"-and change) with a light gun so a 5 shot 3.5" isn't that impressive in comparison.

I suppose I didn't completely elaborate on all of my interests of this matter. I am not so concerned with whether or not accuracy could be better so much as I am concerned with consistent ignition in cold temps with certain powders. Of course i would at least want accuracy to remain the same. Most people who have hunted in very cold sub zero temps with rifles chambered for large cartridges have experienced a miss fire or hang fire at some point. I'm sure a larger flash hole would help to aleviate this issue, but not sure what the other effects would be.

As usual, only a few posts with factual information from personal experiences, or references to experiments actually conducted. The rest, speculation...I can do plenty of speculating and assuming on my own. No offense.