causes of blown primer and primer pocket? have checked oal and load data . 22-250 34 gr varget and 55 gr. nosler bullet. looking for possible causes. thanks

Is this the first time you shot the load, or have you fired it before without issue?

What was the seating pressure like? Any chance the case is too long?

Do you have other rounds you have not fired? I would pull the bullets and check the powder weight - 34 Varget should be fine.

Any chance you loaded the wrong powder?

Blowing a primer out of the case means you had really excessive pressure; can't imagine it would be case length...

you'd have to really cram things in the neck to get pressures high enough to blow primers.
hard enough that chambering the round would take some serious oomph.

I have fired this load for several years. The case length is okay. I used new Nosler Prep brass, and it was the first time loaded. Do not think that wrong powder was used.

That is a starting load on the Hodgdon website so if that amount and type of powder is what was put in the case the pressures should not be high enough to blow primers. If any loaded cases remain, pull the bullets and weigh the powder charge.

I am very concerned that the OP states that he didn’t “think” the wrong powder was used. When loading, does he have more than one powder container on the bench? Does he own powders with a faster burning rate than Varget? When did he last check the calibration of his powder scale?

Soft brass, cases with too-thick necks, there are many potential causes of blown primers/expanded primer pockets. But the simpliest explanation is usually the correct one. Either the wrong powder was used, or the powder charge was excessive.


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did the primer puncture at the firing pin indentation? Was the primer cup extruded into the FP hole (cratered)? was the primer pocket expanded? Was the primer leaking from the edge of the primer cup? The first may be an excessive long or pointed pin, the next suggest pressure, the last,a puncture or leak at the edge of the primer cup might be due to a bad lot of primers. Winchester had some a few years ago with improperly prepared cups that would blow or leak frim the edge of the primer cup even with fairly light loads.

As stated, pressure is NOT always the culprit with blanked/pierced primers.
If the firing pin/spring is gummed up, it can cause the idented part of the primer to ‘blank’, which means it simply falls out.
You MUST after a pierced primer tear down your bolt, that piece of primer cup is generally forced into the FP hole, it will move around and cause a similar issue if not removed.
If it’s not load related, the firing pin protrusion should be measured, it should fall between .045”-.065” depending on rifle type.
I normally set mine to .055” on all rifles I build.

Did you say you switched brass brands?

This could be the reason for your problem, I would check capacity between brands, the heavier brass normally will have LESS capacity, raising pressure.

Cheers.

It could also be just a bad primer. I had one that the cup was not formed correctly. It looked to have been punched out of not enough metal leaving a slit down on side and just to the base. I could not see it when loaded. I always look and feel to make sure the primer is seated fully. Using a Lee priming tool, who looks at each primer!

are the pockets oval shape, and blackened?
If everything else in the load checks out I would suspect the brass is too soft.

You said "new Nosler brass". Did you check case capacity of new brass compared to old? If the new brass is smaller capacity, you could spike pressure.

If it is primer pierced, then pressure should not be a problem and you should be able to re-seat a new primer firmly.

If the primer pocket is damaged, then check case expansion, length, and case head. Is the head stamp embossed on the bolt head (melted brass)? That is a sure sign of high pressure - my guess is that it would be well over 75,000 PSI.

I blew primers 25 years ago in a 243 using the old Barnes X bullets and starting load for 5 gr lighter bullet! I seated out like normal cup and core bullet. I then seated deeper 50 thou off lands solved the problem. Another incident was with a 222Rem different brand of once fired brass & crimped. First 2 shots were flat primers and the third was blown. I still have the remaining 17 rounds in the cupboard after 25 years!

I see a lot of good suggestions here. At least pull one of the bullets from the other cartridges, examine and weigh the powder, and, if all seems well there, go on to the other suggestions. If not, pull all the bullets and be careful what can (if any) you put the powder back in to. If you have a lawn, it might appreciate the fertilizer.

What rifle? I have seen this very same thing in two Savage Axis rifles. Your load almost mirror's what the other rifles had been using.

the rifle is a savage model 10. have shot some of the same reloads with no problem. the day of problem, the reload was exposed to hot outside temperature. love the rifle as it is really accurate for me.

Did you leave it sitting in the sun & it got really warm or was it just the outside temp was hot.

The former could lead to blown primer but not the latter.

quote:

Originally posted by Pepper3:
the rifle is a savage model 10. have shot some of the same reloads with no problem. the day of problem, the reload was exposed to hot outside temperature. love the rifle as it is really accurate for me.