Case head failure

[tmark]

Many things can affect breech pressure such as temperature, amount of powder, and seating depth of the bullet, if the front of the bullet is wedged a little into the initial lands of the rifle, etc.

A combination of these things can elevated chamber pressures higher than expected.

[Matt Anthony]

There were no signs of over pressure, but I'm sure the brass has been reloaded a uncounted number of times. Most times the necks split first or the base no longer goes into the shell holder, then the case hits the scrap bucket. By the way the load was 24.8 gr while the max published is 24.5 gr.

Over the published load is extremely dangerous in MHO! There are so many reasons not to overload your cases that I find anyone who does is looking for future troubles. Constantly putting extreme loads puts undo wear on your weapon and poses a serious trend, "Well it's worked for years, and now it's blown up!" It happens! Mores Law does not work in reloading!
A good example last Sunday was a reloader tried to put the same charge from a 270 WSM in a standard 270. All I can say is 21 stiches, a blown up rifle and now is not allowed to bring his reloaded rounds anylonger to our range. He can only shoot factory loads purchased from the club. He always had a rubber mallet on his bench in case he needed to pound the bolt open! Needless to say, he quit! Good Riddence!

I cannot condone going over the published loads and in fact I stay away from the max loads. All of the 10 calibers I presently reload for do not approach max loadings. Accuracy 99.9% of the time is in the middle of the published starting and max and sometimes the starting load is perfect.

To go and load over published max and state it on this forum is irresponsible as someone without the experience might read it and think it's ok. It's not OK! If you choose to live on the edge, do it in your own back yard. Safety comes first! I believe you should rethink your reloading practices and perhaps read about the dangers of super high pressure loads.
Matt

[tmark]

Good point, Matt. Newcomers to this forum and to reloading may get the idea that exceeding limits is ok if it works for us experienced reloaders.

To those new to reloading, get a good reloading manual (I use Lyman) and follow all safety rules.

I always use the "middle of the road" powder charges. I've never used maximum powder charges. The less stress on the bolt lugs and receiver lugs, the better.

[p246]

It depends on the application and experience of the reloader. I don't go over published data and in most guns stay at least one grain under. In my long range Sender 300 winmag I'm running a full house load. However I've been reloading a long time and I am very comfortable judging signs of overpressure. I also spend a ridiculous amount of time preparing that brass including measuring the case wall thickness with a Neeco gauge on every round. A newer reloader should stay away from Max loads unless they have a good mentor on sight.

Joem my recommendation is to at least back it off to Max or 1/2 grain under my friend. You need to consider you are running brass many reloads at a very high pressure. I know this is not your first rodeo, but its for fun and case head ruptures are anything but.

[tmark]

Remember, too, a max load in thicker-walled military brass will yield higher pressure than the same load in a thinner-walled commercial brass, or so I have been told.

[RED]

I never shoot reloads in a expensive fire arm. Nobody is perfect and everybody makes mistakes. The case in point, I was reloading for a 3 day machine gun shoot. I thought my procedures would result in great product.

1. I was loading once fired LC military surplus brass with pulled MILSURP 55 gr.bullets.

2. I tumbled the brass, resized, and deprimed.

3. Then I trimmed the brass to length on a Dillon Rapid trimmer.

4. I used a tried and true combination of primers, powder, and bullets.

Bottom line, I loaded 1,000 rounds and at the shoot, after 2 or three rounds I experienced a complete head separation.

What did I do wrong???

[tmark]

It is tedious but you have to check the inside of the case for that micro fissure using the bent paper clip technique. That inside crack in the case appears before that incipient ring on the outside to the case.

Or maybe you used a piece of brass reloaded too many times that stretched to the breaking point. But you said it was once reloaded. Was all the brass fired in the same weapon? Different weapons have diverse head space measurements.

[Jim in Salt Lake]

Hi Red, you said your brass was once fired, was it first fired in a machine gun, too? A lot of machine guns have chambers on the big side, I guess for reliability. If your brass was machine gun fired, then fully resized with your sizing die adjusted all the way down, your brass may have been overworked. It started out SAAMI spec size new out of the box, gets machine gun fired and expanded for the big chamber, then you sized it back down to SAAMI spec (or maybe even a little smaller), then the brass was shot again out of a big machine gun chamber. If that's the case, the brass just got stretched too much and ended up getting real thin and weak. If you had to trim the cases quite a bit after re-sizing, that may be a clue, too. That brass that gets trimmed away is brass that is no longer keeping the case walls strong.

[da gimp]

joem & red.......... I'm very interested in one other factor that neither of you mentioned............ How did both of you remove the military primer pocket crimp?

saw a total case head separation back in the 1980's in 5.56 USGI military surplus brass, that the crimp was removed using a primer pocket cutter on an electric drill................ the same damage resulted in that AR as did in joem's........... plus gas & tiny pieces of primer material went back thru the charging handle & got the shooter in the face/white part of his eye & his R hand............ he was an active duty pilot on the BIG E at the time.......... & had to get passed by the flight surgeon to keep flying.

Since then, I picked up a Dillon's primer pocket swager.......... it is extremely fast...... & 100% safe as no metal is removed from the pocket.

[Hefights]

Red, I would ask what was the source of the brass? Are you absolutely sure it was all only once fired? For truly once fired LC brass prepared properly, I would hope that a separation would be highly unlikely. Are we talking about a SAW or AR? Was there damage to the gun? Did you ever shoot the remaining rounds in any gun?

Of course if we want to start talking reliability vs reloading, I would bet LC will be the first to say that they will not guarantee reloaded brass. I shoot reloads in a Garand, 1903, AR, M1A etc, no way I can avoid shooting reloads in an expensive (to me) gun, no way I can afford current ammo prices.

[da gimp]

Maury Krupp has reported excellent results using the RCBS X die set in his .223.... not sure if he uses one in his .30-06 ..... after trimming to proper length before sizing in the X die....... & only resizing that brass in that X die, he's doing little or any retrimming...... if my memory serves me right.................But I'm thinking that he also uses the paperclip test on EVERY piece of rifle brass on after every resizing checking to see if he can feel that defect on the inside of the case............ when in doubt.... throw it out..............hoping he'll chime in on this thread.

[joem]

I remove the crimp with the Dillon Super Swedge. It doesn't remove any metal or cut or alter the depth of the primer pocket. I started really checking my .223 brass and I find that it is at the end of it's useful life. I've been reloading the same batch of cases for years and I'm seeing quite a few case failures on my pistol and rifle brass. Perhaps it's time to scrap them and break out some new brass.

[S.A. Boggs]

Are you using a case gauge to set your resizing die? Too much reduction will result in incipient case head separation.
Sam

[slamfire]

Since you have not posted any pictures, what you call a case head separation is probably different from what I call a case head separation.

These are typical 308 case head separations. For what ever reason, the 5.56 separates fairly high on the case, compared with 308 Win. .

I can’t recall ever hearing of a 5.56 case head separation causing a gas release.



This is a 5.56 typical case head separation, case separating high on the case, except, the rear of the case was extracted, but the front stayed in the chamber. Next round jammed in and the bolt could not be closed. I think this is very dangerous, though I don't see how the firing pin could reach the primer.



These case head failures occurred while I was in the pitts pulling 300 yard rapid fire targets. There was a report of a gun blowup, then a pause, then confused gabbling on the radio, then we ran an alibi string for two targets.

When I get to the firing line two gentleman I know are were having a discussion. It turns out we had two new shooters, and each shooter had been loaned an AR15 and ammunition by Gentleman A. The Match Director was inferring that A’s rifles and ammunition were junk, and A is protesting, saying the rifles and ammunition were fine. The discussion was actually far less concise. You can imagine.

I got to talk to the shooters. Both of them, on the same relay, had the magazines blown out of their rifles during the rapid fire string. And, this will bake your noodle, the next round in the magazine fed into the chamber for each of the shooters. I picked up one of the offending cases, and the pictures below are of it. The other case had been thrown in disgust by the match director well forward of the firing line. Even though two magazines were blown apart, given new magazines, the shooters were able to complete the match with the loaner rifles.

Talking to gentleman A, who I know is a conscientious person, he told me his load, the loading process, and the important point, the brass was military surplus from Scharch.

After the match, I got to talk with other competitor’s and one of them said, he had purchased 223 brass from Scharch and had a number of cases that ruptured through the case head, exactly like the case I was holding.

It is possible that these cases were exposed to ammonia at some point, because it is well known that ammonia compounds cause brass embrittlement

[RED]

First of all the brass I used had crimped primers... That translates to "once fired." I full length resided the brass in a RCBS small length die and then trimmed them on a Dillon Rapid Trim machine and swaged the primer pockets with a Hornady tool.

THE PROBLEM!!! The Dillon Rapid trimmer instructions doesn't tell you that their machine is adjusted for OAL but it does it by setting the shoulder back... 0