What did I do wrong here?

Back to the primer question. It looks to me like the primer was partially pushed out of the case when the shell fired. When the cartridge was set back under pressure into the bolt face the primer was pushed into the case again. That causes the primer cup to balloon out and mushroom at the top as it is pushed back with pressure behind it. That action would promote a rupture along the radius of the cup and the weakness that would cause the split. If the primer pocket is still within specs to hold a new primer then it isn't likely from over-pressure or base head expansion. The root cause could be that the shoulder was simply too far from the front of the chamber and the case moved forward with the firing pin impact.

Other supporting evidence might be a bright line just forward of the web on the case or a slight ring around the inside of the case just forward of the case web.
 
Thanks all again for the responses.

A few questions, if headspace was indeed incorrect and there was too much space between the shoulder and the chamber, shouldn't I have noticed this on a few other rounds as well since I'm using all Hornady brass, all sized using Hornady's FL dies, and the chamber has remained static, nothing has changed there gun was bought brand new.

Should I have checked headspace on the rifle as it came from Ruger?

I used the LE Wilson case gauge on all of these rounds to make sure nothing was glaringly wrong, and they were consistent.

Should I have done more? Honestly asking.

I am positive that the powder charge was set at 42.2 and not overcharged on any of these rounds. I am also positive that they were set to a COL of 2.800 and neck tension was right around .002"... So I guess where I get confused is I don't understand how I caused the "overpressure" to occur which some have suggested?

The only thing that didn't seem consistent was how tightly the primers seated, some seated more loosely than others, but nothing that I would consider "loose" They were still snug. How tight, or how hard of a press should a primer take to seat?

I see what you guys are saying now about the head of the primer cup being mushroomed out, I didn't even notice that until you guys mentioned it. It makes sense how it was explained above that the primer started to unseat before being slammed between the bolt face and the head of the cartridge, if the primer pocket simply wasn't tight enough, could that have caused this?

Not trying to be difficult, so I hope it doesn't come across that way.

I appreciate all the insight from you folks who are a heck of a lot more experienced than I am regarding this.
 
I am positive that the powder charge was set at 42.2 and not overcharged on any of these rounds. I am also positive that they were set to a COL of 2.800 and neck tension was right around .002"... So I guess where I get confused is I don't understand how I caused the "overpressure" to occur which some have suggested?
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I am the fan of cutting down on all that case travel, and then there is the rifle, not all rifles are designed the same, I have rifles I have fired short cases in; meaning the cases were .127" shorter from the shoulder of the case to the case head than the chamber from the shoulder of the chamber to the bolt face. Reloaders believe .127" clearance will cause case head separation, even Hatcher cut a chamber with .060" added to the length of the chamber and then fired minimum length/full length sized ammo in the long chamber without suffering serious case head separation. When it came to rifles he had his choice.

I have to go and hope I will be back; later.

F. Guffey
 
If the case can't move forward in the chamber the primer can't back out. There is always some play between the case and the chamber - even in my partially neck sized cases that have been fired multiple tens of times. It is probably less than .002" and likely less than .001" for my guns but if you are full length sizing where the shell holder hits the bottom of the die there is probably a lot more than .002" of expansion room and depending on the chamber, die, and case caliber it could be well over .010". (common in some "off the shelf" belted magnums)
If you take the time to tune your sizing to fit your chamber you can close up the gap significantly. If you have custom dies made from your chamber reamer then it is easier to get just the right amount of sizing without going too far.
 
So I guess where I get confused is I don't understand how I caused the "overpressure" to occur which some have suggested?
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I'll address my point to this . Let me explain in general terms as to what I meant . To be clear below is general theory and your numbers may be different but I'll try to be in the same ball park

1) COAL . Lets say you are seating your bullet to a COAL of 2.800 . How ever you max possible COAL for your rifle "may" be 2.850 when bullet is touching the lands . This means you have a .050 bullet jump to the lands . If you have a max load or max pressure load with a .050 jump . Upon ignition some gasses can and will blow by and around the bullet before the bullet engages the lands plugging the barrel .

Now if you were to take that same max load and seat the bullet at or into that lands . You will create a pressure spike do to the bullet no longer having that extra room to move forward allowing some start pressure/gases to blow by .

2) Light bullet hold Which is perfectly fine if you work up your load with all the same components from the start and don't change them later . With a .001 or .002 bullet hold it does not take much pressure to pop them loose and forward . Again not a big deal if all your components are the same from the get go

3) Slow burning or hard to ignite powders This is where my ability to explain things gets reduced do to my vocabulary , I just don't have all the correct words to explain in great detail but I'll try . Slow burning powders take a bit of time to really get going or even hard to ignite powder like ball powder can be hard to get burning optimally .

4) Using mixed unknown primers As stated above not all primers are created equal . Some have small flash and others have larger flash while even others like magnum primers have a huge flash . Each one of those will create different pressures all by them selves with magnum primers likely creating the most pressure of them all .

5) The perfect storm , Now lets look at how all of those things can work together to create an issue .

So you have a max pressure load with a .050 jump to the lands and as long as you don't seat the bullet longer your pressure should be safe .

You have minimal bullet hold requiring less energy/pressure to get the bullet moving .

You have a powder that really does not start pushing hard right away

Your using mixed primers that may contain magnum primers and even if not they are still mixed giving you mixed ignition regardless

So you pull the trigger but instead of the primer igniting the powder causing the bullet to move . The pressure of the primer alone causes the bullet to move forward before the powder really starts to ignite . So now at this point your COAL is not 2.800 anymore but really 2.850 or jammed into the lands . At just about the same time your bullet lodges into the lands that slow burning hard to ignite powder really starts to take off . The problem is that powder charge was not designed to be used with the bullet jammed into the lands which now creates a pressure spike above what you originally worked up to .

There has been studies showing slow hard to ignite powders having a secondary pressure spike when the bullet is 1/2 to 3/4 of the way down the barrel . Some think it's the unburned powder slamming into the base of the bullet while still in the bore

Ten throw in excessive head clearance and I'm sure that's not helping much either .

Anyways that's the best my vocabulary can do . I'll add that this is just one possibility and I only think of it based on you POI shift indicating to me there was a rather significant pressure spike compared to the other rounds fired .

Unclenick will come along shortly and slap my theory down in flames but that's my ideas to to what went wrong .
 
Metal God,

Well, you may be overthinking it. All sorts of odd combinations of influences are are possible, of course, but when I suggested the pressure was too high, I carefully added "for that primer". The problem with primers as pressure indicators is they have different cup properties, some being harder and some softer than others, so a pressure that produces a pressure sign with one make of primer may produce none in another. Having powder over the primer rather than forward over the bullet can affect peak pressure and flattening.

Back almost 20 years ago, Winchester got a lot of complaints their rifle primers weren't sensitive enough, so they dropped the nickel plating on the cup, which hardens it some. Subsequently you can find a lot of folks complaining that they flatten easily and some service rifle shooters claim they slamfire more easily. I've not had any issue with the ones I've had, but both Remington, as mentioned, and Winchester have had some bad batches that cracked and leaked, but it must have been limited because I don't recall and actual product recall. They simply offer to replace them. I suspect ADClope got a few samples from such a lot.

The nickel plating on primer cups also adds some corrosion protection. If the brass colored primers were kept near an open kitty litter box, they could be weakened by the ammonia vapors and be more brittle and easily cracked because of that. There's just no way to know. But I would sort all the brass-colored primers out and not use them or else use them only in a plinking load, like a Trail Boss load.

You asked earlier how much pressure would cause that much POI shift, but the cause is usually that change in barrel time caused the bullet to exit at a point when the muzzle is swinging higher and picked up some vertical drift momentum. If it had shifted time to where a muzzle was swinging lower, it might just as easily have been 4" lower. You get reports of that. Raising the pressure and seeing a big jump that can be either up or down. Same for lowering the pressure.


ADClope,

I'd missed your earlier statement indicating you assumed all large rifle primers were the same, but, as indicated, they are not. I've seen up to about 5% velocity change occur just from changing primers. That corresponds to about 5% change in muzzle pressure and about 17% change in breech peak pressure in most common cartridges. So mixed primers is no way to go about getting accuracy or consistency at long range. I would knock the charge down 5% to use up what you have. I would not use any more of the brass-colored ones, however. They may be defective.
 
My thoughts on the matter are to discard them all. Then never buy anything that isn't factory sealed. To finish off, I wouldn't buy anything from a gun show that wasn't absolutely, clearly, factory new and in absolutely certain proper condition.

I wouldn't buy and shoot vintage ammo, opened powder, mixed or unidentified components, etc, I'm not someone who tells myself"it'll probably be okay". One in a thousand chances that the powder is mislabeled or contaminated? If I have a two thousand dollar rifle and priceless eyes attached to questionable reloads, I'm not pulling the trigger.
 
So you pull the trigger but instead of the primer igniting the powder causing the bullet to move . The pressure of the primer alone causes the bullet to move forward before the powder really starts to ignite .
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Reloaders have a cute little saying that is repeaterd over and over, for the most part no one understands what is being said, if it serves no other purpose consider it memory work.

It goes something like this: The firing pin strikes the primer and then everything takes off for the front of the chamber. Everything being the case, powder and bullet; and no one says anything and no one has anything to add or contribute, save one. And he thinks it is a cute saying because if the firing pin strikes the primer logic says the bullet has to get moving to stay up with the case, so? I would think the case would be driven forward and the bullet would sit still; meaning driving the case forward would cause the bullet to seat the bullet deeper.

And then there is the fan of 'all the bullet hold he can get', with 45 pounds of bullet hold there is a chance the bullet will not start to seat before the case got shoved forward. And then there are killer firing pins, he has killer firing pins, his firing pins crush the primer before the case, powder and bullet know their little buddy, the primer has been crushed.

Before the firing pin story there was a cartoon that covered the sequence of events that happened between pulling the trigger and the bullet leaving the barrel. I can only guess primers in the big inning were so tuff the firing pin could not put a dent in the primer until the case was braced against the front of the chamber.

And I have always said there has to be something a reloader does not understand about the firing pin crushing the primer.

F. Guffey
 
It goes something like this: The firing pin strikes the primer and then everything takes off for the front of the chamber.
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that sounds logical

I would think the case would be driven forward and the bullet would sit still; meaning driving the case forward would cause the bullet to seat the bullet deeper.
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also sounds logical

But then I think about things like rimmed cases, and extractors holding the cases, and the teeny tiny amount of actual room for movement that a chambered case has...

and I think of my experience with inertia bullet pullers and revolvers...

and I also think about things like proper neck tension, crimp, and GI ammo with bullets "glued into" the cases.

So it seems to me that concern about cases moving forward when struck by the firing pin, with "disasterous" results, is sound and fury, signifying nothing.

Not saying it cannot happen, dependent on firearm design and tolerances, but why is it a concern??

Now, I can see the concern if somehow pressure from the primer alone drives the bullet into the rifling (stopping it?) BEFORE pressure from the burning powder builds up enough to keep the bullet moving into the rifling and on down the barrel, a pressure spike would result. That situation would (I assume) be about the same as loading too long a round so the bullet jams into the rifling before firing.

seems to me it is an easy thing to avoid, IF IT ACTUALLY IS A PROBLEM.

I make a distinction between things that are "best practice" and things that are "unsafe", and things that are actually "dangerous".
 
I keep coming back to the fact that the bullet struck the target 4" higher than the rest of the rounds. That says over pressure. If the powder charge was right and it wasn't a magnum primer, there is really only one other explanation. When the round was chambered the bullet got shoved much deeper into the cartridge than intended - possibly far enough to compress the powder.
 
It goes something like this: The firing pin strikes the primer and then everything takes off for the front of the chamber.
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So it seems to me that concern about cases moving forward when struck by the firing pin, with "disasterous" results, is sound and fury, signifying nothing.
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Agreed but who's been saying the firing pin pushing the case forward can have disasterous effects ? The case moving fully forward is just something that happens , equal and opposite reaction type of thing ( it's a law , there is no fighting it ). It's just the thing that will help cause case separation when cases are continually sized to short which ultimately can be disasterous.
 
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Agreed but who's been saying the firing pin pushing the case forward can have disasterous effects
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The questions should be; "How can anyone engage a reloader into a conversation about the sequence of events between pulling the trigger and the bullet leaving the barrel without turning them in to snarky reloaders?".

I am the only reloaders that has said; "Wait a minute, I saw an illustrated drawing that was supposed to demonstrate the sequence of event that reminded me of a cartoon". I said I had killer firing pins and that made everyone angry. There was something about time and distance they could not understand.

F. Guffey
 
Time and distance: again, I have fired cases in chambers with .127" clearance between the shoulder of the case and shoulder of the chamber. When I pulled the trigger and the firing pin struck the primer the shoulder on my case did not move; the illustrated cartoon claimed the case was driven forward and the shoulder struck the shoulder of the chamber and again I said; "the shoulder on my case did not move".

I do not have case head space because my cases do not have head space.

F. Guffey
 
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