JeepHammer
Moderator
This is what I expected when the picture posted.
While it's called a 'Crater' in 'Common' terms...
More accurately it would called a 'Donut' around the firing pin strike.
('Craters' don't always have a raised rim around them)
The actual scientific/industry term is 'Extrusion'.
Extrusion is a pressure/die forming process (in most cases) while a 'Crater' is a depression.
The firing pin strike is a 'Crater' (depression).
Amp44 hit the head on the nail.
CCI 400 is a fairly soft primer cup material, so I see donuts with them also using loads that show no other pressure signs, using loads that are well under the maximum 'Safe Published' powder charge weights.
Since the cups don't fail (like a small pistol primer cup might under the same pressure) I don't see any reason to worry about it too much.
I wouldn't give it a second thought at all if it were a safe published charge weight, but fired through a military clone rifle or a 'Lesser' quality rifle.
This is what AMP44 was getting at, military clones and lesser quality rifles OFTEN have oversized firing pin HOLES in the bolt, and softer primers will EXTRUDE into that gap/void without failure.
Military rifles were traditionally less than 'Tight' in machining terms.
While the US military has exacting standards, there has been some real JUNK produced in other parts of the world, and cloned rifles for the civilian market have about ZERO standards.
To this end, military primers are VERY hard, which often leads to inconstancy in ignition, and the reason consistency shooters don't seek out military primers, even though they are available both new manufacture & surplus market.
Personal observations,
I find CCI 400 to be consistent feeding due to their consistent sizing.
I find them to be consistent in ignition, allowing for velocity (FPS) strings to be under 10 FPS at times, all else being equal.
I find variations in string velocities to be small even with aged or mixed batch/lot numbers, they seem to stay consistent for me.
I don't find vairation from humidity changes when the ammo is loaded, but then again, I do pay attention to relative humidity when preparing to load ammo.
I usually load on a high volume progressive machine, and I find CCI in general, 400 in specific to feed nearly flawlessly.
The common CCI 400 primers quite nearly match bench rest primer results, so like Hornady bullets, I would recommend them since they work as advertised.
While it's called a 'Crater' in 'Common' terms...
More accurately it would called a 'Donut' around the firing pin strike.
('Craters' don't always have a raised rim around them)
The actual scientific/industry term is 'Extrusion'.
Extrusion is a pressure/die forming process (in most cases) while a 'Crater' is a depression.
The firing pin strike is a 'Crater' (depression).
Amp44 hit the head on the nail.
CCI 400 is a fairly soft primer cup material, so I see donuts with them also using loads that show no other pressure signs, using loads that are well under the maximum 'Safe Published' powder charge weights.
Since the cups don't fail (like a small pistol primer cup might under the same pressure) I don't see any reason to worry about it too much.
I wouldn't give it a second thought at all if it were a safe published charge weight, but fired through a military clone rifle or a 'Lesser' quality rifle.
This is what AMP44 was getting at, military clones and lesser quality rifles OFTEN have oversized firing pin HOLES in the bolt, and softer primers will EXTRUDE into that gap/void without failure.
Military rifles were traditionally less than 'Tight' in machining terms.
While the US military has exacting standards, there has been some real JUNK produced in other parts of the world, and cloned rifles for the civilian market have about ZERO standards.
To this end, military primers are VERY hard, which often leads to inconstancy in ignition, and the reason consistency shooters don't seek out military primers, even though they are available both new manufacture & surplus market.
Personal observations,
I find CCI 400 to be consistent feeding due to their consistent sizing.
I find them to be consistent in ignition, allowing for velocity (FPS) strings to be under 10 FPS at times, all else being equal.
I find variations in string velocities to be small even with aged or mixed batch/lot numbers, they seem to stay consistent for me.
I don't find vairation from humidity changes when the ammo is loaded, but then again, I do pay attention to relative humidity when preparing to load ammo.
I usually load on a high volume progressive machine, and I find CCI in general, 400 in specific to feed nearly flawlessly.
The common CCI 400 primers quite nearly match bench rest primer results, so like Hornady bullets, I would recommend them since they work as advertised.