Question for gun experts - centerfire primers coming out

The first thing you can do is ensure the chamber is clean and dry of oil. Someone may have been trying to shine it up and not realized they were dumping oil into the chamber while lubing up all the moving parts. This will seal off the brass inside and lead to over pressure.

After that you just have to check the headspace. Ammo nowadays should never be loaded so hot that is causes pressure issues but you wouldn’t be the first or the last to find some.

This, get us some clear pics of the fired primers if you can.

Didn't get any pictures of the primers before I swept them up and trashed them, but they were not smashed. They were complete and just blown out of the case.
This was Federal PowerShok jacketed soft point - the silver primers all have a blue dot on them in brass cases. On sale for $23/box which makes me think they may be culls.
The incidents were random from the 2nd shot throughout the 20th. Every 3rd or 4th shot blew out.

ETA: 270 Win.

quote:

---

Didn't get any pictures of the primers before I swept them up and trashed them, but they were not smashed. They were complete and just blown out of the case.

---

I'm talking about the cases that did not have blown primers.

Were those primers flat? Guessing you didn't notice if you threw them away.

No. There is nothing wrong with that ammo. They’re not culls.

quote:

---

The first thing you can do is ensure the chamber is clean and dry of oil. Someone may have been trying to shine it up and not realized they were dumping oil into the chamber while lubing up all the moving parts. This will seal off the brass inside and lead to over pressure.

---

Good advice. And yes, it could be a headspace issue. It could also be an issue w/ the overall cartridge length being too long or too short. If it's factory ammo, too short would be more likely than too long. I had that happen once on a handload for for my 22 Nosler handgun and a blown primer. I analyzed the rest of the loads in the box and decided the bullet got jammed too deep in the cartridge. I no longer store ammo w/ the bullet down in an ammo box. You could also measure the COAL w/ a dial micrometer and compare w/ factory specs, but sounds like your best option is to take it to a good gunsmith. If you have any of the unshot ammo, bring it w/ you.

I'll mention one other possibility. Did the ammo get to hot? Most powders are sensitive to heat so that chamber pressure and velocity increase as the temperature of the powder goes up. I have to watch for that as I work up loads for my varmint guns during the winter, but on a hunt, the temperature may be as high as 105 degrees. There have been times loads were ok pressure wise during the winter were too high on a hunt in June. After church a few weeks ago, the steering wheel was really hot when I got in my truck. The dashboard thermometer said 105 deg.Using an infrared thermometer, I checked some temps. The dashboard was 183 deg and the steering wheel was 137 deg. This was after the truck had been sitting in full sun only 4 hours. How hot would a box of ammo have been?

What you experienced was a "blown primer." Blown primers indicate excessively high chamber pressures. The question is what has caused it. It's prob not an issue w/ the factory ammo, although it could be. It could also be one of the other issues mentioned. Let the 'smith sort that out. It's never a bad idea to get a second opinion. Good luck. I hope the BAR is usable. Keep us updated.

Check the headspace on it anyway. It takes 30 seconds to do with go/no-go gauges.

It could be bad ammo. It happens. Over pressured, loose primer pockets, short cases, etc. All kinds of ways it can happen and all can be mass produced wrong. My brother had a bad box of factory ammo before. Was loaded too hot. Flat primers and had to beat the bolt open with a hammer.