Flat primers?

[Jimro]

None of those primers looked out of spec to me. If your loads were really hot you would be getting loose primer pockets and gas leakage around the primers.

I think a lot of the "flattened primer" pressure sign came from the old rounded military style primers, it would take a lot of pressure to make them flatten against the bolt face. With the flat bottomed commercial primers we buy, there is much less needed to "flatten" out the small radius at the primer shoulder.

As long as your rifles are shooting those loads fine I would just keep shooting. Brass life is a good indicator of headspace and pressure, if headspace is off you get case separation, if pressure is elevated you get loose primer pockets.

Jimro

[Axelwik]

Here's an example of primer flattening. Notice how the primer is out of round and has "flowed" to fill the radius of the primer pocket.

[Jerry45]

Axelwlk, you picture is 1000 times better that mine and that is “exactly” how my rifle primers look with the exception of the primer strike. My primer stakes are smooth and show no sign of being pushed back out.

My 45/70 (Marlin 1895) looks like factory, however I’m shooting a 300 gr. bullet (light bullet for that caliber) and according to the Lyman 49 I’m shooting right at or just over (don't have the book handy) starting load (37.0 gr, H4198). According the Hodgon’s site starting for the Marlin leaver action should be 40 something gr. up to 60 gr. Around 54 ish primers start flattening. I ladder tested up to 56 gr. (Scope bit me! And I thought I was ready for the recoil). There is no way in hell I was shooting the 60 gr.

Anyway, the more people have posted the less uneasy I’ve become. I can’t thank everyone enough for the help and reassurance. While the primers are flatter that I’d like, I’m reasonable sure the ammo is within safe limits.

[brickeyee]

As along as you don't see cratering you should be okay.

Even cratering is not all that reliable.

It can occur at low pressure from an oversize firing pin hole.

[TNT]

I have never had that problem with .06 I did have it with 44 mag 300 Gr XTP I ran it at 18.5 gr (which is the low side of the loading data) of H110 according to Hornady specs the cases were no stretched or cracked and primers were no backed out and no extraction problems so all is good these were fired out of my Super Blackhawk. But the heavier bullet taking longer to initially leave the seat of the shell and a fast burning powder for short barrel can be attributed to my flat primers. But yours could be due to many things and mind you this is just a opinion, The powder you are using could have a faster burn rate thus making high and fast chamber pressures which could be giving you the flattened primers. H110 does that specifically for pistols a fast burn rate for quick acceleration out of a short barrel. My Theory of the whole thing could be wrong too.