Are deez primers flat?

[Casswick]

Got some boxes here of S&B Tactical 6.5 Creedmoor, 140gn FMJBT. Accuracy is meh, better with a cold barrel. But for factory loads, do these primers look flattened?

[Suck My Glock]

No. Totally normal. When they have been flattened so much that there is no discernible groove or space between primer and brass,...THEN they are flat.

[Joe_Blacke]

Yes those are flattened primers. Not the worst Ive seen by far but there are definite high pressure signs.

Some people only care about extreme flattening and cratering around the firing pin strike caused by the primer trying to flow into the firing pin hole.

I don’t know if the is a universal standard on flattened primer warning signs. Some dont want any flattening, others will take it quite further.

[Creeker]

I’m with SMG. Flat primers indicating overpressure usually run into the grove and often have cratering around the firing pin strike. I suspect what you’re seeing is more of a result of excessive headspace, which would also contribute to the “meh” accuracy. Measure the fired brass against the unfired (better yet, measure the same brass before and after firing) to see how much the shoulder is being pushed.

[Old Jeff H]

I'm with Creeker. LOL. They're flat, but I say it's due to excessive headspace as well.

I've seen the same thing with some 308 ammo that had about 8-10 thousandths of headspace.

[Casswick]

I’m with SMG. Flat primers indicating overpressure usually run into the grove and often have cratering around the firing pin strike. I suspect what you’re seeing is more of a result of excessive headspace, which would also contribute to the “meh” accuracy. Measure the fired brass against the unfired (better yet, measure the same brass before and after firing) to see how much the shoulder is being pushed.

Good info, I hadn't considered this. They were fired from a Ruger Precision gen 2 in 6.5 creedmoor. Factory barrel.

[condition_0ne]

Yes those are very flat. Where you can really tell the difference between hot and "OMG it's gonna blow" is at the edge of the firing pin dimple. Note that on these the edge of the dimple is very sharp and defined. That's getting really close to the limit. Once the edge starts looking rough and uneven and starts standing tall of the overall primer face the material is flowing into the firing pin hole on the bolt face. That's when you're in real trouble and need to back off quite a bit. Otherwise you'll start blowing primers in short order.