What are possible things that can cause blowing primers? Thanks Daniel

Maybe best if you define what you call a "blown primer" first...in at least some detail.

If you’re certain it’s not a pressure issue then it’s usually a firing pin issue. I’ll let others elaborate. Is this the rifle that recently had a Firing pin issue? Or am I thinking of someone else?

Put a hand loaded round into chamber and fire it. Primer comes out of primer seat. New brass,new rifle, not over loaded per several loading books. Has happened 3 times out of about 50 rounds. Happened today and deer went down.
CCI 200. Thanks

WP75169 correct person but not the same rifle or caliber.

One time a few years back, i developed a load for my 6.5CM. It was late summer and temp was 100 degrees out when I did the work up. Ended up being a little hot as per manuals but zero signs of pressure with the load. Shot .75” groups at 200 is the reason I stuck with it.

Later that year there was a small match at JG’s and loaded up a few rounds using all the same components as before. It was later in the fall and temps was in the 70’s but it was a drizzly day with a little bit of rain. Ended up blowing out five of the last 10 shots shooting at 800. Don’t know if it was the humidity or possibly letting the round cook in the chamber too long. Had zero problems with any of them before that.

Is it also puncturing the primer?

Had that happen once with a 243 I inherited and what I thought were factory Remington soft points. Turned out they were handloads in a Remington box and Pappys buddy loaded with what appeared to be powder he mixed together….

No,

Have shot several Remington factory loads from the 1990’s and before. A much higher than acceptable number have been blowing primers. Not punctured just leaking around the primers. I assume it from some form of corrosion in the cartridge. I understand some ammo makes it a long time in shootable condition but all ammo is definitely not created equal.

Did you let the rounds get wet before putting them in the gun? Water outside the brass will over-pressure a round and blow a primer real quick. Always dry your ammo off before putting it in your gun.

Pictures would be helpful. Load description. Primer is proud or out completely? Tried it with a factory load?
Lots of things to look at. Soot on case? Signs of head separation? Brass show signs of dirty or rough chamber? Report/recoil normal on these? Measure the fired brass/compare to factory load or known specimen?. Compare resized brass to factory load.
I'd put it up until I understood to reason for the anomaly.

Need a lot more information. I have cratered primers but never had one "blow out".

Unless it’s federal brass I’m at a loss. Large chamber perhaps. That should be easy to tell by measuring. Your Sinclair Nut will tell the tale.

Get your tools out and start measuring stuff. You are either over pressure, have excessive headspace, or don’t have enough interference between the primer pocket and primer to hold the primer. Don’t make the assumption that advertised maximum charge weights are automatically safe in your rifle. That is incorrect.

What was the velocity in this specific incident?

Bolt or gas gun? I popped a primer due to hot charge in gas gun, Bolt moved too early. Bolt gun, headspace problem. Loose pocket makes it easier. I have had primers fall out after extraction due to loose pockets.

Was the bolt hard to open when you blew a primer? If so, the pressure is way to high.

If this load was with solid copper bullets you can't use cup and core load data. On a .308 I'm usually loading 2-3gr below what manuals show as MAX for the same bullet weight cup and core bullet.

The case will make a HUGE difference. I've got loads that are completely safe in Win cases, but unsafe in Federal.

Well..….... What's the scoop? Figured it out?

Yes, I think so. I decreased load plus re-sized the necks. I had noticed that seating the bullets
I have not shot many rounds since the change but so far no problem.

Primer comes out of primer seat
After opening bolt, loose primer pocket. Happens even in new brass.