Split primers

Anyone ever have a certain brand or lot of primers that split or ruptured without an apparent overload?

I recently changed primers on some .44 mag loads, backed off a little to work up. I was surprised to see an occasional primer leak, split from the firing pin indent outward. No other sign of excess pressure, velocity across the chronograph was fine, extraction was fine. I switched back to the Winchester LP from the Fed 155 and all is well again. The specific load is 22.4 gr. H110 under a 429244; not a weak load by any means, but still a little under book max.

Yes, I know that minor changes in primers, brass, individual gun, etc., can and will all affect pressure. I'm curious if anyone has ever seen this kind of thing before: whether it's a soft primer thing, or it really is an over pressure problem that I'm not quite understanding.

Not a totally uncommen event. I've had the issue a couple of tmes, most recently with Remington SR primers. Sometimes the crack will allow enough hot gas by to divit your bolt face.

I had that happen with some Remington sp primers a couple of years ago.

When it isn't happening, do you get a small puncture right in the middle of the indentation? That would be caused by excessive firing-pin protrusion, and can be cured by very slight stoning of the firing-pin tip, to make it a little more pumpkin shaped than spherical.

Pressure has almost nothing to do with that kind of puncturing. I have had it happen on a previously unfired .38 S&W Webley. I haven't seen a radial split developing from that, but can imagine that it might. I don't think it can be anything to do with excessive pressure, which would show up in a split or cratering around the edge of the indentation.

I had some RWS primers (maybe 1960's vintage; came in trays of 250) that would do that sometimes. Maybe the metal used in the cups for that lot of primers was overly work-hardened or under-annealed.

Other primers in the same shells with the same loads in the same gun worked normally.

I really wish people would be more specific about which primer they are using. Many manufacturers have 2, 3 or even 4 types in any given size. /rant mode off.

I'd load some 44 special power loads and try them in another gun (45acp?). Should tell you if it's the gun or primer. It would be hard for me to dump a 1000 primers but we have to be safe.

Quote:

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Originally Posted by Ken in Iowa

I really wish people would be more specific about which primer they are using. Many manufacturers have 2, 3 or even 4 types in any given size. /rant mode off.

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I can see why Mr elk didn't name a specific primer to curtail the mania that may ensue.

I would shrewdly surmise that he was using Federal 155, and other people's experiences were incidental enough not to really require much in the way of detail. It is a valid point with other threads where people report a primer problem, though.

Yes, the primers in question are Federal 155. They are some older ones I've had around for a few years (or more). I wondered if it could be a firing pin issue (as Ballistics suggests), so I did take the bolt apart and check out the firing pin closely. I think I'll take it apart again and try what you suggest.

The same loads with the same primers works fine in my S&W 629, and the same load with Winchester primers works fine in the rifle. I wonder if it could be a combination of brittle primers and a firing pin a little out of spec. I don't have many of the Federal primers so I'll just use them up in something else, and continue with the Winchester primers.

On the Remington primers I had problems with, They would blow out at the edge and sometimes split to the center. Others would get a hole in the firing pin indent. They were not consistent in where the hole would be.
I swapped out the primers for a different lot number and the problem disappeared. Fortunately this didn't happen with 38 special loads. Only with 9mm.
I finished using them up in 38 special loads.

Photo of the split primers? Thank you for the reply below.

Sorry, that brass has already been sized and the primers in question are long gone. It was always a crack radiating from the firing pin dent outwards.