Primer Blowout

[edistoriverrat]

Hey guys, something I posted elsewhere and did not get an answer. I have never noticed this before until I started saving my cases to maybe reload someday. I found about 25 of my old already fired 30-30 cases and ALL of them have the primer slightly blown out of the case, enough, so that the shell will wobble on a flat surface.
These are all factory new loads out of the box Win 150g hp, Win 130g st, Rem 170g sp core lokt, Win 170g power point.
I checked all the new rounds still in the boxes and all the primers are flush with the case like they are supposed to be.
The rifle in question my uncle gave to me was brand new, he bought it years ago and only fired it 3 times, and put it up, never to be touched again, till I got it.
It is a Marlin 30-30 336 RC.
Is the primer blowout normal or is it something I should check further.
Thanks

 

[BGDave]

Don't know what it means but just went through my stash of 30/30 brass and it looks like most of them are like this. Checked about 50 cases.

 

[doddsracing]

I have two 94 winchesters and have never saw this on any of my brass,checked some cases laying on the bench all are flat .Don`t know what would cause this on a new gun?

 

[bstewrat3]

Sounds like a potential headspace issue or the boltface in your lever action is not seating completely against the base of the brass allowing the primer to protrude upon firing. I am not familiar with how the brass is held by the Marlin though so just throwing the ideas out there.

 

[Nayls47]

Hey guys, something I posted elsewhere and did not get an answer. I have never noticed this before until I started saving my cases to maybe reload someday. I found about 25 of my old already fired 30-30 cases and ALL of them have the primer slightly blown out of the case, enough, so that the shell will wobble on a flat surface.
These are all factory new loads out of the box Win 150g hp, Win 130g st, Rem 170g sp core lokt, Win 170g power point.
I checked all the new rounds still in the boxes and all the primers are flush with the case like they are supposed to be.
The rifle in question my uncle gave to me was brand new, he bought it years ago and only fired it 3 times, and put it up, never to be touched again, till I got it.
It is a Marlin 30-30 336 RC.
Is the primer blowout normal or is it something I should check further.
Thanks

I would have to agree with bstewrat3, and have the headspace checked since it is doing the same thing to all those different factory loads.

 

[edistoriverrat]

Thanks everyone, glad to know at least somebody else has the same problem. I really hate to let anyone mess with the rifle, and it does shoot quite well, so I will probably just leave alone for now. As long as it don't start blowing them out more than half way anyway.

 

[BudS]

It's low pressure that typically causes it, not high pressure.
If there isn't enough pressure, the primer will remain backed out.
It could be excess headspace, but you would usually see some cracked or broken cases.

If you have ever fired wax or rubber practice rounds, the primers will almost always be backed out due to very low pressures.

 

[Leo]

BudS is right about it being pronounced by low chamber pressure. High pressure would be stretching the brass and slamming the case head back against the breech. Pretty common on a 30/30 lever gun. Low pressure, loose headspace tolerance and thin, soft brass all contribute. I do not think you are in any danger, I have seen this for 40 years on lots of different lever guns.

If we scraped out all the model 94 winchesters that had sloppy headspace, I do not think there would be any left.

 

[lon]

I've read that there is a lot of "spring" in a '94 action, and see it with every load in my pre-WWII rifle.