Had a Case-Head separation today

T

Tom68

New member
So, here is the data, which has actually worked somewhat well in the past:

.308 Winchester
Hornady 150 gr. FMJBT
46.0 gr RL-15*
Federal Cases (loaded once before, I believe)
CCI 200 primer
OAL 2.800 (canalure centered on the case neck)


So, looking back at the previous 14 fired cases, I had ignored pressure signs in the flattened primers (although not terribly so). So I obviously have a pressure problem with this particular mix of components. One culprit may be in the sizing; it was unusually difficult to clear the expander ball on many of the cases. Could that have anything to do with pressure? and what could have been causing that problem in the first place? I wasn't sizing any differently than the previous thousands of bottleneck cases; in fact, the set ring on my sizing die is still locked where it has been for eons, using the same single-stage press...which allows only a slight cam-over. Everything about the case-prep process was identical to the way I've been doing it for about 7 years.

second question.... what to do with the rest of the 85 primed cases after I pull down the powder and bullets? Would it be safe to drop down to a 110 grain bullet with an absolute minimum charge, and just use for fouling rounds? Or does the community say play the safe route and toss 'em?




*Speer manual lists their 150 gr FMJBT for 45.0-49.0 of RL-15; Alliant doesn't have an exact match for the Hdy 150 gr FMJBT, but they also agree with the 49 gr max for the Speer soft point. I don't have access to Hornady load data, but I would be shocked if it 46 gr of RL-15 was anywhere near their book max for the 150 gr FMJBT.
 
The Hornady 150 grian FMJ BT is a stubby bullet. When the cannelure is centered on a 2.05" trimmed length .308 Win case's mouth, the COL should be 2.700", according to the Hornady databook. This gives you a seating depth (for the cylindrical bearing surface) of about 0.250". The maximum load in the Hornady manual is 47.2 grains in a Hornady/Frontier case, which is usually a little more roomy than a Federal case; perhaps 1 grain more powder capacity. Plus, Federal case heads have a reputation for being soft, so if you put the two together, you could have pressure signs.

A primer's condition tells you if that particular primer type was bothered by the pressure or not, but doesn't tell you what the pressure was in the case. Primer cups aren't calibrated like copper crusher slugs, and even those can err by 25%. So, I think your load looks OK, in principle, but the particular cases may not be holding up. Also, primer cups can get flat if your headspace is on the long side, independent of whether or not the pressure is within SAAMI limits.

Difficulty clearing the expander ball could be because you have it set up too high into the die so it starts to expand the neck before it clears the neck sizing portion of the die well enough. It can also be due to over-resizing thick necks. Resizing could seem hard if you are resizing too far and pushing the shoulder back more than necessary. 0.002" setback from the as-fired size is usually enough, even for a self-loader. If you don't have a case comparator, a spacer and caliper will do. Simply adjust your sizing die position until that is all the shorter it makes the case. Most commercial ammunition is about 0.002" smaller than a SAAMI minimum chamber length, which is how we know that is an adequate sizing effort. The less you push the shoulder back during resizing, the longer the case will last before head separation threatens.

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You need to bend the tip of a paperclip or use a dental pick to probe your other cases in the area where the head separated on your case that came apart. Look for a depression in that area where the brass thins during stretching. If you can feel it clearly, the case should be tossed in the recycle bin and not reloaded again.
 
Nick, I was hoping you would reply, and your answer did not disappoint. As far as sizing goes, one method I used early on was to minimally FL resize, and then check to see if the empty case would chamber in the rifle. If the bolt wouldn't lock properly, give another 1/8 to 1/4 turn and try again. In addition to the spacer perhaps I could try that again and re lock the ring.

Thanks for the load data, Redford. I obviously could have backed well below 10% of max.

So, what is the opinion for repurposing the primed cases for downloads (then tossing them)?
 
My thoughts are toss them first. Then load some new brass.

I personally enjoy Norma brass more than others, but Hornady match brass has worked well so far in the 308 Win for me.

I've never shot any factory 308 Win ammo, so I can't tell you what to expect with that.
 
Federal brass is pretty soft. My Hornady 9 and 10 lists 47.2 as max, so I'm not surprised at your experience. With WW cases and CCI 200, I can feel a little primer flow with my fingernail at 45 grains with 150 Interlocks.
 
I guess the first thing I would do is compare your fired case size to your already sized cases using a comparator or the spacer Unclenick suggested . Once we know that comparison we can better figure this out . As you described your sizing method , you should not be over sizing your cases . That does not mean you are not just that method tends to work well enough to get several loadings from one case , even federal

Let me ask this . How many rounds have you shot of these once before reloaded cases and how many of those had the head separation ?

If most of them have had the issue I'd pull some of those loaded rounds and do the paper clip scratch test and see if they are already showing signs of head stretch . If only one of many fired has had head separation I'd check the cases fired for the second time with the paper clip and see if they are showing the signs of imminent head separation . If not then maybe you just got and old case mixed in with the good ones .

I'm constantly separating my cases ( thousands ) of multiple calibers and when priming I still have the odd case come through I missed , it happens you know .

I will add this though . If you are getting cam over on a standard shell holder . You either have a tight for spec chamber or you are bumping the shoulders back to far . If I size a case using a standard shell holder with cam over . The case is sized down .006 shorter then my GO gauge measures . That's almost to much for any chamber if you are hoping for long brass life .
 
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Tom68 wrote:
46.0 gr RL-15*
Click to expand...

How did you come up with this load?

Did you follow proper load development procedures by beginning at the Starting Load (it's called that for a reason) and then incrementally working up? Or did you pick a number from the range of charges given?

If the former, why did you ignore pressure signs when they appeared?

If the latter, then thank the Lord that your gun wasn't damaged and you weren't injured (disfigured or permanently handicapped) and start developing your loads according to the process given in the reloading manuals.
 
Could be you are about to progress to a next level of reloading.
Nobody likes tossing brass,or head separations.

You said you adjusted your sizing die down so the case would barely chamber,then gave it 1/8 to 1/4 turn.

Your dies are thread 14 threads per inch. 1/14th of an inch is a bit over .071
So 1/8 turn is about .009 past the bolt closing. 1/4 turn is twice that.

Taken at what you said,you may be adding .009 to .017 head clearance...or case stretch.
For good brass life,in a bolt gun,.002 is ideal..004 would be fine.

Your firing pin drives the case forward.Case expands,grabs chamber walls.
Pressure forces primer back to the bolt face.

More pressure tries to pull the case in two at approx. the chamber mouth. It stretches ...all at that one ring.

Case head blows back to bolt face,the protruding primer gets flattened.

For 20 something dollars you can get a Wilson bushing case gauge.

If you se it as intended,you can resize your cases to SAAMI length.
That's between the high and low step.

Having said that,you will get all sorts of opinions about the bushing gauge from people who think it is a "plunk gauge" to qualify loaded ammo. Its not.
They do not know what they are talking about.

Probe your cases as Unclenick suggested. IMO,if you find more stretch rings,just scrap them.

Buy a new lot of brass,AND the Wilson gauge. And read the instructions.
Good luck!
 
Tom68 said:
Nick, I was hoping you would reply, and your answer did not disappoint. As far as sizing goes, one method I used early on was to minimally FL resize, and then check to see if the empty case would chamber in the rifle. If the bolt wouldn't lock properly, give another 1/8 to 1/4 turn and try again. In addition to the spacer perhaps I could try that again and re lock the ring.
Click to expand...

1/8 to 1/4 of a turn is too coarse. The thread is 14 tpi. You are adjusting in step of 0.009" to 0.018". High power rifle will start having headspace problem when the head clearance is more than 0.005". 1/16 of a turn or finer is more like it. I actually do 1/48 to 1/24 of a turn. Down to 0.0015" that is.

-TL


Sent from my SM-G930T using Tapatalk
 
You said you adjusted your sizing die down so the case would barely chamber,then gave it 1/8 to 1/4 turn.
Click to expand...

If that's the case you're are correct . I how ever read his post to say he tried to chamber if it didn't he turned the die in 1/8 to 1/4 then resized and tried to chamber again . Repeat until he was able to chamber . Many folks use that method with good results . I do agree that if he was right on the edge of the case chambering and then turned the die in a full 1/4 turn . That would result in the case/shoulder being bumped back farther then he would have wanted . This is why I think it best the OP make some measurements of his fire formed cases and his FL sized cases . That should give us a better understanding where he really is in all this .
 
I had a crack near where a pressure ring would be in a case that was on its 2nd firing.

LC 12 Brass
41 gr IMR 4064
CCI 200 primer.
175 gr Match kin
OAL 2.800

This load is chronographed , and verified by Quickload to be relatively lower pressure. It's my AR-10 match load.

I am still using that batch of brass with a group of 100 on thier 7th firing annealed at 3rd and 6th load. Dental pick examination revealed no ring internally. I resize my AR cases about 0.0045".

So, somtimes stuff just happens. I have used plenty of Federal brass and have no negative opinions Check everything that has been mentioned. It may just be a fluke
 
Federal Cases (loaded once before, I believe)
Click to expand...
While folks have different opinions on Federal brass,I'll give those who like it the benefit of the doubt.As I have avoided it,I can't claim experience. I'm sure,if it is once fired,brand is not the issue.

But "once fired" can mean many things.If you bought "once fired" it could be anything. "once fired" is sold as such in good faith,but its range cleanup.
Some shooters who have stretch ringed brass shoot it one more time then leave it lay. Some 7.62 NATO is only fired once...through a machine gun.

Unless you bought factory loads or virgin brass.do you really have any idea of the history of your brass?

Your brass is what it is,good or bad,but it does not necessarily relate to your reloading technique.

I re-read your post.You are using a very appropriate power and charging one grain over starting load per the data available. I really do not think excessive pressure is the problem.

Excessive force over the expander ball ...Hmm. Use a nylon bore brush to brush the necks. Imperial,the sizing wax folks,make a dry lube for inside the neck.
If you are using Forster dies..tell me. They set up differently.There could be a problem.

Hard to learn from used brass,unless the history is yours.

I'd start fresh with new.And get the bushing gauge.
 
Pick up a ruptured cartridge extractor. Will save a lot of aggravation should the case get stuck in the chamber after you pull the head off...
 
wow, lots of good replies.

hdwhit, I came up with the 46.0 some time ago, relying primarily on Speer data. I was not trying to optimize accuracy necessarily, just to provide inexpensive fouling and warming rounds. I started with 45.0 (start load), and added 45.5 and 46.0 and stopped there. 46.0 provided the best of those three. I successfully used this load twice before with no issues whatsoever; first I used Hornady brass, and Federal the second time. Since I was so far at the bottom end of the published range, I didn't start over when switching headstamps. The first time that was not a problem, but the second time evidently was.

I know the history of my brass as well as I record it, or failing that, can remember it, as almost all of it started out as fresh factory ammunition (I have bought new cases on two occasions). I had a 18 month hiatus in which my reloading kit was stored, and I shot a few hundred rounds of Hornady, Federal, and Lapua brass (the latter being Creedmoor branded. I highly recommend it for those who choose to not handload). I save the latter for load development, and had been using Federal for the more expendable.

the 1/4 to 1/8 turn figure that I stated earlier was an estimate based on memory from several years ago. At the time I was doing that I was consulting the Speer manual and other published sources, so I'm confident that what I was doing at the time was much more precise that my memory is.

Something that I failed to mention that may add perspective to my situation is that I had to return the gun to Savage shortly after buying it. The chamber was too tight and I was experiencing pressure signs at the bottom end of the scale with nearly every powder I tried. Savage agreed with that prognosis and re-cut the chamber. Therefore if I use brass from the "original" chamber, then it could easily have different properties than stuff fired in the "re-cut" chamber. I was neck-sizing before having the chamber re-cut, but have been FL sizing since. I actually thought of going back to neck sizing--but only for the brass that I am certain was fired through the "new" chamber. But, that may explain the difficulty in the expander ball...brass initially fired through a "tight" chamber, then FL resized and fired in a longer chamber... wouldn't the brass "flow" forward, thinning the head area and making the necks thicker? just a thought.
 
Moving goalposts!
We started with 100 rds of brass and a head separation.
Now we have maybe hundreds of rounds? Lapua ,Hornady,Federal,etc...
A "before chamber",an "after chamber",and dies that have not had the lock ring moved in seven years.
And we are wondering if brass is flowing forward and thickening the necks?
You give measurements you have taken.I suppose you could measure the necks?
The 100 rds of Federal we started with,of the 14 fired ,how many have stretch rings inside? Is this little "lot" of 100 rds where your problems lie? Was it fired in the old chamber? Point: If its problematic brass with two or three stretch rings out of 15,and its history is vague,why worry about it? But the brass is once fired?
You do as you choose.I gave those problems up. I minimize or eliminate variables.I buy 500 or 1000 WW virgin brass. I work with 100 lots to load. That 100 splits necks or gets stretched,I scrap it.All 100. I pull another 100 of the same lot from stash.
And I set my head clearance with a gauge and measuring tools to a known amount.
 
I wasn't sizing any differently than the previous thousands of bottleneck cases; in fact, the set ring on my sizing die is still locked where it has been for eons,
Click to expand...

Bad habits: If in my position there is a die with the lock ring secured to the die, it is not my die. I secure the die to the press with the lock ring. I adjust my dies every time I use them. I do not adjust my dies for minimum length/full length sizing, I sized my cases to the chamber I know the length of the chamber from the shoulder to the bolt face.

I am 'THE' fan of cutting down on all that case travel. Reloaders struggle with understanding what happens to the case between pulling the trigger and the bullet leaving the barrel. Explaining case head separation/understanding is the perfect example.

And then there is that thing with moving the shoulder, I no longer ask, "HOW?"

F. Guffey
 
My take is that FC brass is both soft and its heavy which means it has less capacity.

While its nice brass to work with, I only use it as 5 shot and throw away. It just does not hold up.

My brother and I have had experience with cracked cases in that above the base area with NO indication inside of a lip.

When you adjust your die the way you are (and it is the recommended ) you are pushing your shoulder back, the maximum distance.

That in turn stretches the base are when its fired.

The solution to that is to look up the process for minimum shoulder bump back (you need more in a semi auto so its tougher go if you shoot those

I would think you have fired that more than twice, but as Mississippi noted, sometimes a bad case.

The only FC I am shooting right now is for a 270 and its the only large quantity I have. I will pick up RP or PPU for that. Both do much better than FC.

PPU is still ongoing, but RP has proven to be as good as Lapua in my shooting. PPU so far looks good but have not run any of them through the number of cycle the RP has gone through.
 
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