Primer pockets opening up and ejector pin stuck in bolt face.

[jsteiger]

Rust, I see what you are saying. Makes perfect sense!

RonAKA, due to the unavailability of primers for a while there, I have used a few different types. This could be what put this load over the edge. What I should have done when changing primers is back off the charge and work back up again, especially being at the max end of the load.

After going back and reading all of your posts again, I see a lot of things that I've done wrong. The most important thing I'm realizing is that I don't know as much about all this as I thought. This load that I worked into was shooting so well out of this gun, but what good is a great load if it's not safe. I've learned a new respect for pressure and will deffinitely start paying closer attention to it and all of the things that can affect it.

 

[RonAKA]

This chart on primers was posted by another. May provide some help in trying to find out what happened.

 

[MQ1]

If you bumped the shoulder back too much on an already hot load, that could have caused your immediate problem.

I had a .223 with a known safe load that I once oversized the brass on. The Winchester cases survived, but showed significant pressure signs that I did not notice until something bad happened.

I shot a number of Hornady cases, and until one separated, I didn't know there was an issue to look for. On inspection, nearly every fired Hornady case obviously was on the verge of separation, and major flat primers, and yes...on the last one the primer fell out. On inspection of the remaining rounds, I had oversized the cases a significant amount, obviously creating a bad situation.
After I realized what the problem was, I had to go back and pull down the remaining 200 rounds I had screwed up... One of these days I'll photograph the the cases I kept to remind me to measure twice....

I agree with German on the Benchmark.

MQ1

 

[BoydAllen]

Since the subject of shoulder bump has come up, I will go off topic a little, and recommend that everyone that reloads for bottle necked cases should have a way to MEASURE bump. There are a couple of caliper attachments that do a good job. Just remember to deprime before making your initial measurement, since the fired primer can protrude and/or have a crater that can have a significant effect when making measurements to the nearest .001". Telling reloaders to set there FL dies by feel is a bad idea, because the person giving the advice usually has no way to know the relative sizes of the chamber and FL die. If the chamber is small relative to the die, you can set the shoulder back excessively getting to the "right feel". If the die can not get you to the right feel without excessive bump, you need a different die...period. I am always amazed at how common it is for shooters to argue with the idea that they should measure something that is so important, especially given the affordability of the tools that are used to do it. Case head separations are caused by repeated excessive shoulder bump. Also, as brass if fired and sized it work hardens, and will probably require a different die setting to get to the same bump. For this reason, cases should be used and reloaded in sets that are treated in a uniform manner, and die settings should be checked for each different batch. If you have your die set for old cases that have been fired many times,and use the same die setting for new, softer, brass, you will probably set the shoulders back too far. Another thing, the case can be within spec. for length and still be too long from shoulder to end of neck, if the case was near max. and the shoulder was set back too far. In this case, the case is driven forward when the cartridge is fired, and at that point the neck can be wedged into the bullet by the angle at the end of the neck portion of the chamber, raising pressure significantly.

 

[cliffy]

The ONLY primer pockets that opened-up have come from Nosler brass, in my experience. I don't believe a primer of ANY given-power can cause this. An oversized (drilled) primer release hole can cause blown primers (pierced primers via firing pin). Use the correct or slightly slower powder than what is creating primer problems. A FLATTENED primer face after firing is NORMAL in most rifle applications. Rounded edges on a rifle primer after firing indicates a TOO light powder charge. A difficult to remove case, after firing, indicates too high of pressure most likely due to a power overcharge, or too fast burning of powder charge. Primers, per say, cannot cause or add to these problems. The difference betwixt a "standard" and a "magnum" primer is not so great as to cause difficulty removing spent cases. This is my observation through many thousands of fired rounds. Cliffy

 

[BoydAllen]

A friend, who was known for his impatience, had a couple of custom actioned rifles, one each in .22-250 AE, and the other a Cheetah MKI. He had worked up loads that reflected the chronograph numbers that he had read of in magazine articles. What he did not know is that, because of their case shapes, AE cartridges do not show classic progressive signs of pressure on fired primers, and are less prone to getting a tight bolt as well. As a result he did not know that his loads were at the ragged edge of what his cases would hold. He had worked up the loads with Federal primers, and being a thrifty sort, when these ran short, and having an abundance of Winchester primers on hand, switched to these. The next trip to the range he blew primers out of cases, so forcefully that he damaged the jewel triggers. Luckily, neither he nor the rifles were hurt beyond the trigger damage. When I remonstrated with him about not dropping his load back, and doing another workup with the new primers, his answer was that he did not have the time, which was bull. He just did not want to be bothered. This happened twice, on the same rifles. The second time I told his gunsmith that he should refuse to work on them any more, since by doing so he was enabling such poor and dangerous judgment to control a situation where someone could be seriously hurt. Any time that you change a component, drop back and rework the load.

 

[Kenny474]

Primers are all different and all have different amounts of power stored in them and release it at different rates. That is why you can tune loads with primers to a degree. (I don't know if I worded that correctly) Some produce higher velocity than others in the same load with only the primer being changed.

Cliffy, when you are running the ragged edge with certain powders in certain cases, even the smallest change of any variable can cause drastic change in pressure. Primers being included in that.

I don't see you as a person to take risks or run on the edge of peak pressure, so you probably have never encountered this. When you go by the book 100% and are overly cautious, you don't often see the results that others running peak pressure will.

 

[moorepower]

I believe it was in Shooting Times, but this was tested I believe on a 7mm RM within the last couple years and there was a huge jump in pressure from the lowest to the highest with primers. If I recall it was somewhere between 5-7k psi. I also wonder if the brass has not grown too long and is crimping in the bullet. What most fail to realize when using book loads, if you are not using the same brass, primer and bullet with the same jump, chamber, ect, it is not exactly the same.